The Jurassic ( ) is a
geologic period
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronol ...
and
stratigraphic system that spanned from the end of the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
Period million years ago (Mya) to the beginning of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
Period, approximately Mya. The Jurassic constitutes the middle period of the
Mesozoic Era
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising ...
and is named after the
Jura Mountains
The Jura Mountains ( , , , ; french: Massif du Jura; german: Juragebirge; it, Massiccio del Giura, rm, Montagnas da Jura) are a sub-alpine mountain range a short distance north of the Western Alps and mainly demarcate a long part of the Frenc ...
, where
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
strata from the period were first identified.
The start of the Jurassic was marked by the major
Triassic–Jurassic extinction event
The Triassic–Jurassic (Tr-J) extinction event, often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, , and is one of the top five major extinction events of the Phanerozoic eon, profoundly affect ...
, associated with the eruption of the
Central Atlantic Magmatic Province
The Central Atlantic magmatic province (CAMP) is the Earth's largest continental large igneous province, covering an area of roughly 11 million km2. It is composed mainly of basalt that formed before Pangaea broke up in the Mesozoic Era, near the ...
. The beginning of the
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian.
The Toarcian ...
Stage started around 183 million years ago and is marked by an extinction event associated with widespread
oceanic anoxia,
ocean acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
, and elevated temperatures likely caused by the eruption of the
Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined.
By the beginning of the Jurassic, the
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...
Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
had begun
rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics.
Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...
ing into two landmasses:
Laurasia
Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
to the north and
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
to the south. The climate of the Jurassic was warmer than the present, and there were no
ice caps
In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets.
Description
Ice caps are not constrained by topographical features ...
. Forests grew close to the poles, with large arid expanses in the lower latitudes.
On land, the fauna transitioned from the Triassic fauna, dominated jointly by
dinosauromorph
Dinosauromorpha is a clade of avemetatarsalian archosaurs (reptiles closer to birds than to crocodilians) that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lag ...
and
pseudosuchia
Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...
n
archosaur
Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...
s, to one dominated by
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s alone. The first birds appeared during the Jurassic, evolving from a branch of
theropod
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...
dinosaurs. Other major events include the appearance of the earliest lizards and the evolution of
theria
Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes.
Ch ...
n mammals.
Crocodylomorphs
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction.
During Mesozoic and early Cenozoic times, cr ...
made the transition from a terrestrial to an aquatic life. The oceans were inhabited by
marine reptiles
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment.
The earliest marine reptile mesosaurus (not to be confused with mosasaurus), arose in the Permian period during the ...
such as
ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s and
plesiosaur
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
s, while
pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
s were the dominant flying
vertebrates
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
. The first sharks, rays and crabs also first appeared during the period.
Etymology and history
![Alexandre Brongniart](https://upload.wikimedia.org/wikipedia/commons/1/1c/Alexandre_Brongniart.jpg)
The
chronostratigraphic
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.
The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geologic ...
term "Jurassic" is linked to the
Jura Mountains
The Jura Mountains ( , , , ; french: Massif du Jura; german: Juragebirge; it, Massiccio del Giura, rm, Montagnas da Jura) are a sub-alpine mountain range a short distance north of the Western Alps and mainly demarcate a long part of the Frenc ...
, a forested
mountain range
A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...
that mainly follows the
France–Switzerland border
The France–Switzerland border is long. Its current path is mostly the product of the Congress of Vienna of 1815, with the accession of Geneva, Neuchâtel and Valais to the Swiss Confederation, but it has since been modified in detail, the la ...
. The name "Jura" is derived from the
Celtic
Celtic, Celtics or Keltic may refer to:
Language and ethnicity
*pertaining to Celts, a collection of Indo-European peoples in Europe and Anatolia
**Celts (modern)
*Celtic languages
**Proto-Celtic language
* Celtic music
*Celtic nations
Sports Fo ...
root ''*jor'' via
Gaulish
Gaulish was an ancient Celtic languages, Celtic language spoken in parts of Continental Europe before and during the period of the Roman Empire. In the narrow sense, Gaulish was the language of the Celts of Gaul (now France, Luxembourg, Belgium ...
''*iuris'' "wooded mountain", which was borrowed into
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
as a name of a place and evolved into ''Juria'' and finally ''Jura''.
During a tour of the region in 1795, German naturalist
Alexander von Humboldt
Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister, p ...
recognized
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
deposits within the Jura Mountains as geologically distinct from the
Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
aged
Muschelkalk
The Muschelkalk (German for "shell-bearing limestone"; french: calcaire coquillier) is a sequence of sedimentary rock strata (a lithostratigraphic unit) in the geology of central and western Europe. It has a Middle Triassic (240 to 230 million ye ...
of Southern Germany, but he erroneously concluded that they were older. He then named them ('Jura limestone') in 1799.
In 1829, the French naturalist
Alexandre Brongniart
Alexandre Brongniart (5 February 17707 October 1847) was a French chemist, mineralogist, geologist, paleontologist, and zoologist, who collaborated with Georges Cuvier on a study of the geology of the region around Paris. Observing fossil content ...
published a book entitled ''Description of the Terrains that Constitute the Crust of the Earth or Essay on the Structure of the Known Lands of the Earth.'' In this book, Brongniart used the phrase ''terrains jurassiques'' when correlating the "Jura-Kalkstein" of Humboldt with similarly aged
oolitic limestones in Britain, thus coining and publishing the term "Jurassic".
The German geologist
Leopold von Buch
Christian Leopold von Buch (26 April 1774 – 4 March 1853), usually cited as Leopold von Buch, was a German geologist and paleontologist born in Stolpe an der Oder (now a part of Angermünde, Brandenburg) and is remembered as one of the most im ...
in 1839 established the three-fold division of the Jurassic, originally named from oldest to the youngest: the
Black Jurassic
The Black Jurassic or Black Jura (german: Schwarzer Jura) in earth history refers to the lowest of the three lithostratigraphic units of the South German Jurassic, the latter being understood not as a geographical, but a geological term in the ...
,
Brown Jurassic
The Brown Jurassic or Brown Jura (german: Brauner Jura or ''Braunjura'') in earth history refers to the middle of the three lithostratigraphic units of the South German Jurassic, the latter being understood not as a geographical, but a geological ...
, and
White Jurassic
The White Jurassic or White Jura (german: Weißer Jura or ''Weißjura'') in earth history refers to the upper of the three lithostratigraphic units of the South German Jurassic, the latter being understood not as a geographical, but a geological t ...
. The term "
Lias
Lias may refer to:
Geology
* Lias Formation, a geologic formation in France
*Lias Group, a lithostratigraphic unit in western Europe
* Early Jurassic, an epoch
People
* Godfrey Lias, British author
* Mohd Shamsudin Lias (born 1953), Malaysian ...
" had previously been used for strata of equivalent age to the Black Jurassic in England by
William Conybeare and
William Phillips William Phillips may refer to:
Entertainment
* William Phillips (editor) (1907–2002), American editor and co-founder of ''Partisan Review''
* William T. Phillips (1863–1937), American author
* William Phillips (director), Canadian film-make ...
in 1822.
The French
palaeontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Alcide d'Orbigny
Alcide Charles Victor Marie Dessalines d'Orbigny (6 September 1802 – 30 June 1857) was a French naturalist who made major contributions in many areas, including zoology (including malacology), palaeontology, geology, archaeology and anthrop ...
in papers between 1842 and 1852 divided the Jurassic into ten stages based on
ammonite
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
and other fossil assemblages in England and France, of which seven are still used, but none has retained its original definition. The German geologist and palaeontologist
Friedrich August von Quenstedt
Friedrich August von Quenstedt (July 10, 1809 – December 21, 1889), was a German geologist and palaeontologist.
Life
Von Quenstedt was born at Eisleben in Saxony, and educated at the Humboldt University of Berlin. After a period as assistant ...
in 1858 divided the three series of von Buch in the
Swabian Jura
The Swabian Jura (german: Schwäbische Alb , more rarely ), sometimes also named Swabian Alps in English, is a mountain range in Baden-Württemberg, Germany, extending from southwest to northeast and in width. It is named after the region of ...
into six subdivisions defined by ammonites and other fossils.
The German palaeontologist
Albert Oppel
Carl Albert Oppel (19 December 1831 – 23 December 1865) was a German paleontologist.
History
He was born at Hohenheim in Württemberg, on 19 December 1831. He first went to the University of Tübingen, where he graduated with a Ph.D. i ...
in his studies between 1856 and 1858 altered d'Orbigny's original scheme and further subdivided the stages into
biostratigraphic
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...
zones, based primarily on ammonites. Most of the modern stages of the Jurassic were formalized at the Colloque du Jurassique à Luxembourg in 1962.
Geology
The Jurassic Period is divided into three
epochs
In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured.
The moment of epoch is usually decided by ...
: Early, Middle, and Late. Similarly, in
stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks.
Stratigrap ...
, the Jurassic is divided into the
Lower Jurassic
The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma&nb ...
,
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...
, and
Upper Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987.
In European lithostratigraphy, the name ...
series
Series may refer to:
People with the name
* Caroline Series (born 1951), English mathematician, daughter of George Series
* George Series (1920–1995), English physicist
Arts, entertainment, and media
Music
* Series, the ordered sets used in ...
. Geologists divide the rocks of the Jurassic into a
stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithostrati ...
set of units called
stages
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* S ...
, each formed during corresponding time intervals called ages.
Stages can be defined globally or regionally. For global stratigraphic correlation, the
International Commission on Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigra ...
(ICS) ratify global stages based on a
Global Boundary Stratotype Section and Point
A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...
(GSSP) from a single
formation
Formation may refer to:
Linguistics
* Back-formation, the process of creating a new lexeme by removing or affixes
* Word formation, the creation of a new word by adding affixes
Mathematics and science
* Cave formation or speleothem, a secondar ...
(a
stratotype A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the stan ...
) identifying the lower boundary of the stage.
The ages of the Jurassic from youngest to oldest are as follows:
Stratigraphy
![Fm Lajas Maquina Cura](https://upload.wikimedia.org/wikipedia/commons/6/60/Fm_Lajas_Maquina_Cura.jpg)
Jurassic stratigraphy is primarily based on the use of ammonites as
index fossils
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bi ...
. The
first appearance datum
First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particu ...
of specific ammonite
taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
is used to mark the beginnings of stages, as well as smaller timespans within stages, referred to as "ammonite zones"; these, in turn, are also sometimes subdivided further into subzones. Global stratigraphy is based on standard European ammonite zones, with other regions being calibrated to the European successions.
Early Jurassic
The oldest part of the Jurassic Period has historically been referred to as the Lias or Liassic, roughly equivalent in extent to the Early Jurassic, but also including part of the preceding
Rhaetian
The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...
. The Hettangian Stage was named by Swiss palaeontologist
Eugène Renevier
Eugène Renevier (26 March 18314 May 1906) Swiss geologist, was born at Lausanne, Switzerland, as a descendant of a noble family.
After about three years of study at the polytechnical school of Stuttgart, Renevier in 1851 went to Geneva to study ...
in 1864 after
Hettange-Grande
Hettange-Grande (; ; Lorraine Franconian: ''Grouss-Hetténgen'') is a commune in the Moselle department in Grand Est in north-eastern France.
The town gives its name to the Hettangian age, the earliest age of the Jurassic period of the geologic ...
in north-eastern France.
The GSSP for the base of the Hettangian is located at the Kuhjoch Pass,
Karwendel Mountains,
Northern Calcareous Alps
The Northern Limestone Alps (german: Nördliche Kalkalpen), also called the Northern Calcareous Alps, are the ranges of the Eastern Alps north of the Central Eastern Alps located in Austria and the adjacent Bavarian lands of southeastern Germany. ...
, Austria; it was ratified in 2010. The beginning of the Hettangian, and thus the Jurassic as a whole, is marked by the
first appearance
In American comic books and other stories with a long history, first appearance refers to the first issue to feature a fictional character. These issues are often highly valued by collectors due to their rarity and iconic status.
Reader intere ...
of the ammonite ''
Psiloceras spelae tirolicum'' in the
Kendlbach Formation
The Kendlbach Formation is a Late Triassic (latest Rhaetian) to Early Jurassic (Hettangian) geological formation in Austria and Italy. It contains the Global Boundary Stratotype Section and Point (GSSP) for the Hettangian stage (the first stage o ...
exposed at Kuhjoch. The base of the Jurassic was previously defined as the first appearance of ''Psiloceras planorbis'' by Albert Oppel in 1856–58, but this was changed as the appearance was seen as too localised an event for an international boundary.
The Sinemurian Stage was first defined and introduced into scientific literature by Alcide d'Orbigny in 1842. It takes its name from the French town of
Semur-en-Auxois
Semur-en-Auxois () is a commune of the Côte-d'Or department in eastern France. The politician François Patriat, the engineers Edmé Régnier L'Aîné (1751–1825) and Émile Dorand (1866-1922), and the Encyclopédiste Philippe Guéneau de M ...
, near
Dijon
Dijon (, , ) (dated)
* it, Digione
* la, Diviō or
* lmo, Digion is the prefecture of the Côte-d'Or department and of the Bourgogne-Franche-Comté region in northeastern France. the commune had a population of 156,920.
The earlies ...
. The original definition of Sinemurian included what is now the Hettangian. The GSSP of the Sinemurian is located at a cliff face north of the hamlet of
East Quantoxhead
East Quantoxhead is a village in the district of Somerset West and Taunton, from West Quantoxhead, east of Williton, and west of Bridgwater, within the Quantock Hills Area of Outstanding Natural Beauty in Somerset, England.
History
Above the ...
, 6 kilometres east of
Watchet
Watchet is a harbour town, civil parish and electoral ward in the county of Somerset, England, with a population in 2011 of 3,785. It is situated west of Bridgwater, north-west of Taunton, and east of Minehead. The town lies at the mouth of ...
,
Somerset
( en, All The People of Somerset)
, locator_map =
, coordinates =
, region = South West England
, established_date = Ancient
, established_by =
, preceded_by =
, origin =
, lord_lieutenant_office =Lord Lieutenant of Somerset
, lord_ ...
,
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, within the
Blue Lias
The Blue Lias is a geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassi ...
, and was ratified in 2000. The beginning of the Sinemurian is defined by the first appearance of the ammonite ''
Vermiceras quantoxense.''
Albert Oppel in 1858 named the Pliensbachian Stage after the hamlet of
Pliensbach in the community of
Zell unter Aichelberg
Zell unter Aichelberg is a municipality in the district of Göppingen in Baden-Württemberg in southern Germany.
Geographical location
Between Stuttgart and Ulm, on the western edge of the district Göppingen, lies the municipality of Zell unter ...
in the
Swabian Alb
The Swabian Jura (german: Schwäbische Alb , more rarely ), sometimes also named Swabian Alps in English, is a mountain range in Baden-Württemberg, Germany, extending from southwest to northeast and in width. It is named after the region of ...
, near
Stuttgart
Stuttgart (; Swabian: ; ) is the capital and largest city of the German state of Baden-Württemberg. It is located on the Neckar river in a fertile valley known as the ''Stuttgarter Kessel'' (Stuttgart Cauldron) and lies an hour from the ...
, Germany. The GSSP for the base of the Pliensbachian is found at the Wine Haven locality in
Robin Hood's Bay
Robin Hood's Bay is a small Yorkshire coast fishery, fishing village and a bay located in the North York Moors National Park, south of Whitby and north of Scarborough, North Yorkshire, Scarborough on the coast of North Yorkshire, England. Ba ...
,
Yorkshire
Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...
, England, in the
Redcar Mudstone Formation
The Redcar Mudstone Formation is a geological formation in North Yorkshire, England. Part of the Lias Group, it was deposited in the Hettangian to Pliensbachian stages of the Early Jurassic. The lithology consists of fissile mudstones and siltstone ...
, and was ratified in 2005. The beginning of the Pliensbachian is defined by the first appearance of the ammonite ''
Bifericeras donovani''.
The village
Thouars
Thouars () is a commune in the Deux-Sèvres department in western France. On 1 January 2019, the former communes Mauzé-Thouarsais, Missé and Sainte-Radegonde were merged into Thouars.
It is on the River Thouet. Its inhabitants are known as ...
(Latin: ''Toarcium''), just south of
Saumur
Saumur () is a commune in the Maine-et-Loire department in western France.
The town is located between the Loire and Thouet rivers, and is surrounded by the vineyards of Saumur itself, Chinon, Bourgueil, Coteaux du Layon, etc.. Saumur statio ...
in the
Loire Valley of
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, lends its name to the Toarcian Stage. The Toarcian was named by Alcide d'Orbigny in 1842, with the original locality being Vrines quarry around 2 km northwest of Thouars. The GSSP for the base of the Toarcian is located at
Peniche, Portugal
Peniche () is a seaside municipality and a city located in the Leiria District of Central Portugal. It has 26,431 inhabitants, in an area of 77.55 km2. The city itself has a population of about 15,600 inhabitants.
The present mayor is Henriqu ...
, and was ratified in 2014. The boundary is defined by the first appearance of ammonites belonging to the subgenus ''
Dactylioceras
''Dactylioceras'' was a widespread genus of ammonites from the Lower Jurassic period, approximately 180 million years ago ( mya).
Etymology
The name ''Dactylioceras'' comes from the Greek ''dactyl'', meaning “finger”, and refers to the shell ...
''
(''Eodactylites'')''.''
Middle Jurassic
The Aalenian is named after the city of
Aalen
Aalen () is a former Free Imperial City located in the eastern part of the German state of Baden-Württemberg, about east of Stuttgart and north of Ulm. It is the seat of the Ostalbkreis district and is its largest town. It is also the large ...
in Germany. The Aalenian was defined by Swiss geologist
Karl Mayer-Eymar
Karl David Wilhelm Mayer-Eymar (29 July 1826 – 25 February 1907) was a Franco-Swiss paleontologist and geologist known for his work on classifying the stratigraphy of the Tertiary into 12 stages. He was born Karl Mayer but added the anagram Eymar ...
in 1864. The lower boundary was originally between the dark clays of the Black Jurassic and the overlying clayey sandstone and
ferruginous
The adjective ferruginous may mean:
* Containing iron, applied to water, oil, and other non-metals
* Having rust on the surface
* With the rust (color)
See also
* Ferrous, containing iron (for metals and alloys) or iron(II) cations
* Ferric, cont ...
oolite of the Brown Jurassic sequences of southwestern Germany.
The GSSP for the base of the Aalenian is located at
Fuentelsaz
Fuentelsaz is a municipality located in the province of Guadalajara, Castile-La Mancha, Spain. According to the 2004 census
A census is the procedure of systematically acquiring, recording and calculating information about the members of a g ...
in the
Iberian range
Iberian refers to Iberia. Most commonly Iberian refers to:
*Someone or something originating in the Iberian Peninsula, namely from Spain, Portugal, Gibraltar and Andorra.
The term ''Iberian'' is also used to refer to anything pertaining to the fo ...
near
Guadalajara, Spain
Guadalajara (, ) is a city and municipality in Spain, located in the autonomous community of Castilla–La Mancha. It is the capital of the Province of Guadalajara.
Lying on the central part of the Iberian Peninsula at roughly metres above sea ...
, and was ratified in 2000. The base of the Aalenian is defined by the first appearance of the ammonite ''
Leioceras opalinum''.
Alcide d'Orbigny in 1842 named the Bajocian Stage after the town of
Bayeux
Bayeux () is a Communes of France, commune in the Calvados (department), Calvados Departments of France, department in Normandy (administrative region), Normandy in northwestern France.
Bayeux is the home of the Bayeux Tapestry, which depicts ...
(Latin: ''Bajoce'') in Normandy, France. The GSSP for the base of the Bajocian is located in the Murtinheira section at
Cabo Mondego
Cabo Mondego is a cape located in central western Portugal bordering the Atlantic Ocean. It is the westernmost point of the Serra da Boa Viagem and is located three kilometers north of Figueira da Foz
Figueira da Foz (), also known as Figueir ...
, Portugal; it was ratified in 1997. The base of the Bajocian is defined by the first appearance of the ammonite ''
Hyperlioceras mundum.''
The Bathonian is named after the city of
Bath, England, introduced by Belgian geologist
d'Omalius d'Halloy in 1843, after an incomplete section of oolitic limestones in several quarries in the region. The GSSP for the base of the Bathonian is Ravin du Bès, Bas-Auran area,
Alpes de Haute Provence, France; it was ratified in 2009. The base of the Bathonian is defined by the first appearance of the ammonite ''
Gonolkites convergens'', at the base of the
''Zigzagiceras zigzag'' ammonite zone''.''
The Callovian is derived from the
Latinized name of the village of
Kellaways in
Wiltshire
Wiltshire (; abbreviated Wilts) is a historic and ceremonial county in South West England with an area of . It is landlocked and borders the counties of Dorset to the southwest, Somerset to the west, Hampshire to the southeast, Gloucestershire ...
, England, and was named by Alcide d'Orbigny in 1852, originally the base at the contact between the
Forest Marble Formation
The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weisham ...
and the
Cornbrash Formation
The Cornbrash Formation is a Middle Jurassic geological formation in England. It ranges in age from Bathonian to Callovian, the uppermost part of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from the for ...
. However, this boundary was later found to be within the upper part of the Bathonian.
The base of the Callovian does not yet have a certified GSSP. The working definition for the base of the Callovian is the first appearance of ammonites belonging to the genus ''
Kepplerites
''Kepplerites'' is a moderately evolute ammonite from the lower Callovian (upper Middle Jurassic) included in the Stephanoceratoidea.
Inner whorls are finely ribbed and have a flattened or grooved venter, the outer whorl has a rounded venter wit ...
.
''
Upper Jurassic
The Oxfordian is named after the city of
Oxford
Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
in England and was named by Alcide d'Orbigny in 1844 in reference to the
Oxford Clay
The Oxford Clay (or Oxford Clay Formation) is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifical ...
. The base of the Oxfordian lacks a defined GSSP.
W. J. Arkell in studies in 1939 and 1946 placed the lower boundary of the Oxfordian as the first appearance of the ammonite ''
Quenstedtoceras mariae'' (then placed in the genus ''
Vertumniceras''). Subsequent proposals have suggested the first appearance of ''
Cardioceras redcliffense'' as the lower boundary.
The village of
Kimmeridge
Kimmeridge () is a small village and civil parish on the Isle of Purbeck, a peninsula on the English Channel coast in Dorset, England. It is situated about south of Wareham and west of Swanage. In 2013 the estimated population of the civil p ...
on the coast of
Dorset
Dorset ( ; archaically: Dorsetshire , ) is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth, Christchurch and Poole and Dorset (unitary authority), Dors ...
, England, is the origin of the name of the Kimmeridgian. The stage was named by Alcide d'Orbigny in 1842 in reference to the
Kimmeridge Clay
The Kimmeridge Clay is a sedimentary deposit of fossiliferous marine clay which is of Late Jurassic to lowermost Cretaceous age and occurs in southern and eastern England and in the North Sea. This rock formation is the major source rock for North ...
. The GSSP for the base of the Kimmeridgian is the Flodigarry section at
Staffin Bay on the
Isle of Skye
The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated ...
,
Scotland
Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...
, which was ratified in 2021. The boundary is defined by the first appearance of ammonites marking the boreal Bauhini Zone and the subboreal Baylei Zone.
The Tithonian was introduced in scientific literature by Albert Oppel in 1865. The name Tithonian is unusual in geological stage names because it is derived from
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...
rather than a place name.
Tithonus
In Greek mythology, Tithonus ( or ; grc, Τιθωνός, Tithonos) was the lover of Eos, Goddess of the Dawn. He was a prince of Troy, the son of King Laomedon by the Naiad Strymo (Στρυμώ). The mythology reflected by the fifth-century vas ...
was the son of
Laomedon
In Greek mythology, Laomedon (; grc, Λαομέδων means "ruler of the people") was a Trojan king, son of Ilus and thus nephew of Ganymede and Assaracus.
Family
Laomedon's mother was variously identified as Eurydice,Apollodorus3.12.2/ ...
of
Troy
Troy ( el, Τροία and Latin: Troia, Hittite language, Hittite: 𒋫𒊒𒄿𒊭 ''Truwiša'') or Ilion ( el, Ίλιον and Latin: Ilium, Hittite language, Hittite: 𒃾𒇻𒊭 ''Wiluša'') was an ancient city located at Hisarlik in prese ...
and fell in love with
Eos
In ancient Greek mythology and religion, Eos (; Ionic and Homeric Greek ''Ēṓs'', Attic ''Héōs'', "dawn", or ; Aeolic ''Aúōs'', Doric ''Āṓs'') is the goddess and personification of the dawn, who rose each morning from her home at ...
, the Greek goddess of
dawn
Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizo ...
. His name was chosen by Albert Oppel for this
stratigraphical stage because the Tithonian finds itself hand in hand with the dawn of the Cretaceous. The base of the Tithonian currently lacks a GSSP.
The working definition for the base of the Tithonian is the first appearance of the ammonite genus ''
Gravesia''.
The upper boundary of the Jurassic is currently undefined, and the Jurassic–Cretaceous boundary is currently the only system boundary to lack a defined GSSP. Placing a GSSP for this boundary has been difficult because of the strong regionality of most biostratigraphic markers, and lack of any
chemostratigraphic events, such as
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
excursions (large sudden changes in
ratios of isotopes), that could be used to define or correlate a boundary.
Calpionellid
Calpionellids are an extinct group of eukaryotic single celled organisms of uncertain affinities. Their fossils are found in marine rocks of Upper Jurassic to Lower Cretaceous age. They were planktic organisms with urn-shaped, calcitic tests t ...
s, an enigmatic group of
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
ic
protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
s with urn-shaped calcitic
tests
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film), ...
briefly abundant during the latest Jurassic to earliest Cretaceous, have been suggested to represent the most promising candidates for fixing the Jurassic–Cretaceous boundary In particular, the first appearance ''
Calpionella alpina
''Calpionella'' is an extinct genus of calpionellid, a group of single celled eukaryotes. ,'' co-inciding with the base of the eponymous Alpina subzone, has been proposed as the definition of the base of the Cretaceous. The working definition for the boundary has often been placed as the first appearance of the ammonite ''
Strambergella jacobi,'' formerly placed in the genus ''
Berriasella'', but its use as a stratigraphic indicator has been questioned, as its first appearance does not correlate with that of ''C. alpina''.
Mineral and hydrocarbon deposits
The Kimmeridge Clay and equivalents are the major
source rock
In petroleum geology, source rock is rock which has generated hydrocarbons or which could generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been depos ...
for the
North Sea oil
North Sea oil is a mixture of hydrocarbons, comprising liquid petroleum and natural gas, produced from petroleum reservoirs beneath the North Sea.
In the petroleum industry, the term "North Sea" often includes areas such as the Norwegian Sea and ...
.
The Arabian Intrashelf Basin, deposited during the Middle and Late Jurassic, is the setting of the world's largest oil reserves, including the
Ghawar Field
Ghawar (Arabic: الغوار) is an oil field located in Al-Ahsa Governorate, Eastern Province, Saudi Arabia. Measuring (some ), it is by far the largest conventional oil field in the world, and accounts for roughly a third of the cumulative ...
, the world's largest oil field. The Jurassic-aged Sargelu and Naokelekan formations are major source rocks for
oil in Iraq. Over 1500 gigatons of Jurassic coal reserves are found in north-west China, primarily in the
Turpan-Hami Basin and the
Ordos Basin
The Ordos Plateau, also known as the Ordos Basin or simply the Ordos, is a highland sedimentary basin in northwest China with an elevation of , and consisting mostly of land enclosed by the Ordos Loop, a large northerly rectangular bend of the Y ...
.
Impact structures
Major impact structures include the
Morokweng impact structure
The Morokweng impact structure is an impact structure buried beneath the Kalahari Desert near the town of Morokweng in South Africa's North West province, close to the border with Botswana.
Description
The impact structure is at least about ...
, a 70 km diameter impact structure buried beneath the Kalahari desert in northern South Africa. The impact is dated to the Tithonian, approximately 146.06 ± 0.16 Mya. Another major structure is the
Puchezh-Katunki crater
Puchezh-Katunki is a meteor crater located in the Nizhny Novgorod Oblast of the Volga Federal District, Russia. It is in diameter. Argon–argon dating has constrained the age of formation to be 195.9 ± 1.0 million years old, placing it ...
, 40 kilometres in diameter, buried beneath
Nizhny Novgorod Oblast
Nizhny Novgorod Oblast (russian: link=no, Нижегородская область, ''Nizhegorodskaya oblast''), is a federal subjects of Russia, federal subject of Russia (an oblast). Its administrative center is the types of inhabited localiti ...
in western Russia. The impact has been dated to the Sinemurian, 195.9 ± 1.0 Ma.
Paleogeography and tectonics
![Opening of western Indian Ocean 150 Ma](https://upload.wikimedia.org/wikipedia/commons/2/29/Opening_of_western_Indian_Ocean_150_Ma.png)
At the beginning of the Jurassic, all of the world's major landmasses were coalesced into the
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...
Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
, which during the Early Jurassic began to break up into northern supercontinent
Laurasia
Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...
and the southern supercontinent
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
.
The rifting between North America and Africa was the first to initiate, beginning in the early Jurassic, associated with the emplacement of the
Central Atlantic Magmatic Province
The Central Atlantic magmatic province (CAMP) is the Earth's largest continental large igneous province, covering an area of roughly 11 million km2. It is composed mainly of basalt that formed before Pangaea broke up in the Mesozoic Era, near the ...
.
During the Jurassic, the North
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
remained relatively narrow, while the South Atlantic did not open until the Cretaceous.
The continents were surrounded by
Panthalassa
Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During th ...
, with the
Tethys Ocean
The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...
between Gondwana and Asia. At the end of the Triassic, there was a
marine transgression
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, which results in flooding. Transgressions can be caused by the land sinking or by the ocean basins filling ...
in Europe, flooding most parts of central and western Europe transforming it into an archipelago of islands surrounded by shallow seas. During the Jurassic, both the North and South Pole were covered by oceans.
Beginning in the Early Jurassic, the Boreal Ocean was connected to the proto-Atlantic by the "Viking corridor" or Transcontinental Laurasian Seaway, a passage between the
Baltic Shield
The Baltic Shield (or Fennoscandian Shield) is a segment of the Earth's crust belonging to the East European Craton, representing a large part of Fennoscandia, northwestern Russia and the northern Baltic Sea. It is composed mostly of Archean and ...
and
Greenland
Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
several hundred kilometers wide.
Madagascar and Antarctica began to rift away from Africa during the late Early Jurassic in association with the eruption of the
Karoo-Ferrar large igneous provinces, opening the western
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
and beginning the fragmentation of Gondwana. At the beginning of the Jurassic, North and South America remained connected, but by the beginning of the Late Jurassic they had rifted apart to form the Caribbean Seaway, also known as the Hispanic Corridor, which connected the North Atlantic Ocean with eastern Panthalassa. Palaeontological data suggest that the seaway had been open since the Early Jurassic.
As part of the
Nevadan orogeny
The Nevadan orogeny occurred along the western margin of North America during the Middle Jurassic to Early Cretaceous time which is approximately from 155 Ma to 145 Ma. Throughout the duration of this orogeny there were at least two different kin ...
, which began during the Triassic, the
Cache Creek Ocean
The Cache Creek Ocean, formerly called Anvil Ocean, is an inferred ancient ocean which existed between western North America and offshore continental terranes between the Devonian and the Middle Jurassic.
Evolution of the concept
First propo ...
closed, and various
terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...
s including the large
Wrangellia Terrane
The Wrangellia Terrane (named for the Wrangell Mountains, Alaska) is a crustal fragment (terrane) extending from the south-central part of Alaska and along the Coast of British Columbia in Canada. Some geologists contend that Wrangellia extends ...
accreted onto the western margin of North America. By the Middle Jurassic the
Siberian plate and the North China-Amuria block had collided, resulting in the closure of the
Mongol-Okhotsk Ocean
The Mongol-Okhotsk Ocean also known as the Khangai-Khantey Ocean was an ancient ocean, present during the Mesozoic. Oceanic rocks from the ancient ocean floor are preserved in the Mongol-Okhotsk suture zone extending through Mongolia to the Sea of ...
.
![Pacific Ocean 180Ma](https://upload.wikimedia.org/wikipedia/commons/9/95/Pacific_Ocean_180Ma.jpg)
During the Early Jurassic, around 190 million years ago, the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
originated at the
triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can b ...
of the
Farallon,
Phoenix
Phoenix most often refers to:
* Phoenix (mythology), a legendary bird from ancient Greek folklore
* Phoenix, Arizona, a city in the United States
Phoenix may also refer to:
Mythology
Greek mythological figures
* Phoenix (son of Amyntor), a ...
, and
Izanagi
Izanagi (イザナギ/伊邪那岐/伊弉諾) or Izanaki (イザナキ), formally known as
, is the creator deity (''kami
are the deities, divinities, spirits, phenomena or "holy powers", that are venerated in the Shinto religion. They can b ...
tectonic plates
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
, the three main
oceanic plates of Panthalassa. The previously stable triple junction had converted to an unstable arrangement surrounded on all sides by
transform fault
A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subductio ...
s because of a kink in one of the plate boundaries, resulting in the formation of the Pacific Plate at the centre of the junction. During the Middle to early Late Jurassic, the
Sundance Sea
The Sundance Sea was an epeiric sea that existed in North America during the mid-to-late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western ...
way, a shallow
epicontinental sea
An inland sea (also known as an epeiric sea or an epicontinental sea) is a continental body of water which is very large and is either completely surrounded by dry land or connected to an ocean by a river, strait, or "arm of the sea". An inland s ...
, covered much of northwest North America.
![OoidSurface01](https://upload.wikimedia.org/wikipedia/commons/c/cd/OoidSurface01.jpg)
The
eustatic sea level
The eustatic sea level is the distance from the center of the earth to the sea surface. An increase of the eustatic sea level can be generated by decreasing glaciation, increasing spreading rates of the mid-ocean ridges or more mid-oceanic ridges. ...
is estimated to have been close to present levels during the Hettangian and Sinemurian, rising several tens of metres during the late Sinemurian–Pliensbachian before regressing to near present levels by the late Pliensbachian. There seems to have been a gradual rise to a peak of ~75 m above present sea level during the Toarcian. During the latest part of the Toarcian, the sea level again dropped by several tens of metres. It progressively rose from the Aalenian onwards, aside from dips of a few tens of metres in the Bajocian and around the Callovian–Oxfordian boundary, peaking possibly as high as 140 metres above present sea level at the Kimmeridgian–Tithonian boundary. The sea levels falls in the late Tithonian, perhaps to around 100 metres, before rebounding to around 110 metres at the Tithonian–Berriasian boundary.
The sea level within the long-term trends across the Jurassic was cyclical, with 64 fluctuations, 15 of which were over 75 metres. The most noted
cyclicity in Jurassic rocks is fourth order, with a periodicity of approximately 410,000 years.
During the Early Jurassic the world's oceans transitioned from an
aragonite sea to a
calcite sea chemistry, favouring the dissolution of
aragonite
Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including prec ...
and precipitation of
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
. The rise of calcareous
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
during the Middle Jurassic profoundly altered ocean chemistry, with the deposition of
biomineralized plankton on the ocean floor acting as a
buffer
Buffer may refer to:
Science
* Buffer gas, an inert or nonflammable gas
* Buffer solution, a solution used to prevent changes in pH
* Buffering agent, the weak acid or base in a buffer solution
* Lysis buffer, in cell biology
* Metal ion buffer
* ...
against large CO
2 emissions.
Climate
The climate of the Jurassic was generally warmer than that of present, by around 5 °C to 10 °C, with
atmospheric carbon dioxide
Carbon dioxide in Earth's atmosphere is a trace gas that plays an integral part in the greenhouse effect, carbon cycle, photosynthesis and oceanic carbon cycle. It is one of several greenhouse gases in Earth's atmosphere that are contributing t ...
likely four times higher. Forests likely grew near the poles, where they experienced warm summers and cold, sometimes snowy winters; there were unlikely to have been ice sheets given the high summer temperatures that prevented the accumulation of snow, though there may have been mountain glaciers.
Dropstone
Dropstones are isolated fragments of rock found within finer-grained water-deposited sedimentary rocks or pyroclastic beds. They range in size from small pebbles to boulders. The critical distinguishing feature is that there is evidence that the ...
s and
glendonites in northeastern Siberia during the Early to Middle Jurassic indicate cold winters.
[Alt URL]
/ref> The ocean depths were likely 8 °C warmer than present, and coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Co ...
s grew 10° of latitude further north and south. The Intertropical Convergence Zone
The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal e ...
likely existed over the oceans, resulting in large areas of desert and scrubland in the lower latitudes between 40° N and S of the equator. Tropical rainforest
Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...
and tundra
In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...
biomes are likely to have been rare or absent.
The beginning of the Jurassic was likely marked by a thermal spike corresponding to the Triassic–Jurassic extinction and eruption of the Central Atlantic magmatic province. The first part of the Jurassic was marked by the Early Jurassic cool interval between 199 and 183 million years ago. It has been proposed that glaciation was present in the Northern Hemisphere during the Pliensbachian. There was a spike in global temperatures of around 4–8 °C during the early part of the Toarcian corresponding to the Toarcian Oceanic Anoxic Event and the eruption of the Karoo-Ferrar large igneous province
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...
s in southern Gondwana, with the warm interval extending to the end of the Toarcian around 174 million years ago.
During the Toarcian warm interval, ocean surface temperatures likely exceeded 30 °C, and equatorial and subtropical (30°N–30°S) regions are likely to have been extremely arid, with temperatures in the interior of Pangea likely in excess of 40 °C. The Toarcian warm interval is followed by the Middle Jurassic cool interval between 174 and 164 million years ago. This is followed by the Kimmeridgian warm interval between 164 and 150 million years ago. The Pangean interior had less severe seasonal swings than in previous warm periods as the expansion of the Central Atlantic and western Indian Ocean provided new sources of moisture. The end of the Jurassic was marked by the Tithonian–early Barremian cool interval, beginning 150 million years ago and continuing into the Early Cretaceous.
Climatic events
Toarcian Oceanic Anoxic Event
The Toarcian Oceanic Anoxic Event (TOAE), also known as the Jenkyns Event, was an episode of widespread oceanic anoxia during the early part of the Toarcian Age, c. 183 Mya. It is marked by a globally documented high amplitude negative carbon isotope
Carbon (6C) has 15 known isotopes, from to , of which and are stable. The longest-lived radioisotope is , with a half-life of years. This is also the only carbon radioisotope found in nature—trace quantities are formed cosmogenically by t ...
excursion, as well as the deposition of black shales
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...
and the extinction and collapse of carbonate-producing marine organisms, associated with a major rise in global temperatures.
The TOAE is often attributed to the eruption of the Karoo-Ferrar large igneous provinces and the associated increase of carbon dioxide concentration in the atmosphere, as well as the possible associated release of methane clathrate
Methane clathrate (CH4·5.75H2O) or (8CH4·46H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amou ...
s. This likely accelerated the hydrological cycle
The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly cons ...
and increased silicate weathering
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is al ...
, as evidenced by an increased amount of organic matter of terrestrial origin found in marine deposits during the TOAE. Groups affected include ammonites, ostracod
Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...
s, foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and ot ...
, bivalves
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
, cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that th ...
ns, and especially brachiopods
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, whi ...
, for which the TOAE represented one of the most severe extinctions in their evolutionary history. While the event had significant impact on marine invertebrates, it had little effect on marine reptiles. During the TOAE, the Sichuan Basin
The Sichuan Basin (), formerly transliterated as the Szechwan Basin, sometimes called the Red Basin, is a lowland region in southwestern China. It is surrounded by mountains on all sides and is drained by the upper Yangtze River and its tributa ...
was transformed into a giant lake, probably three times the size of modern-day Lake Superior
Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...
, represented by the Da’anzhai Member of the Ziliujing Formation
The Ziliujing Formation is a geological formation in China, It is Early Jurassic in age. It is part of the stratigraphy of the Sichuan Basin. The dinosaur ''Gongxianosaurus'' and indeterminate theropod material are known from the Dongyuemiao Mem ...
. The lake likely sequestered ∼460 gigatons (Gt) of organic carbon and ∼1,200 Gt of inorganic carbon during the event. Seawater pH, which had already substantially decreased prior to the event, increased slightly during the early stages of the TOAE, before dropping to its lowest point around the middle of the event. This ocean acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
is the probable cause of the collapse of carbonate production. Additionally, anoxic conditions were exacerbated by enhanced recycling of phosphorus back into ocean water as a result of high ocean acidity and temperature inhibiting its mineralisation into apatite; the abundance of phosphorus in marine environments caused further eutrophication and consequent anoxia in a positive feedback loop.
End-Jurassic transition
The end-Jurassic transition was originally considered one of eight mass extinctions, but is now considered to be a complex interval of faunal turnover, with the increase in diversity of some groups and decline in others, though the evidence for this is primarily European, probably controlled by changes in eustatic sea level.
Flora
End-Triassic extinction
There is no evidence of a mass extinction of plants at the Triassic–Jurassic boundary. At the Triassic–Jurassic boundary in Greenland, the sporomorph (pollen and spores) record suggests a complete floral turnover. An analysis of macrofossil floral communities in Europe suggests that changes were mainly due to local ecological succession
Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire) or more or less.
Bacteria allows for the cycling of nutrients such as ca ...
. At the end of the Triassic, the Peltaspermaceae
Peltaspermaceae is a natural family of seed ferns (Pteridospermatophyta) widespread in both northern and southern hemispheres coal measures of Permian and Triassic age. Peltasperms persisted in a relictual distribution in Patagonia during the Ea ...
became extinct in most parts of the world, with ''Lepidopteris
''Lepidopteris'' ("scaly fern") is a form genus for leaves of Late Permian to Late Triassic Period Pteridospermatophyta, or seed ferns, which lived from around 260 to 200 million years ago in what is now Australia, Antarctica, India, South Amer ...
'' persisting into the Early Jurassic in Patagonia. ''Dicroidium
''Dicroidium'' is an extinct genus of fork-leaved seed ferns that were widely distributed over Gondwana during the Triassic (). Their fossils are known from South Africa, the Arabian Peninsula, Australia, New Zealand, South America, Madagascar ...
'', a seed fern that was a dominant part of Gondwanan floral communities during the Triassic, also declined at the Triassic–Jurassic boundary, surviving as a relict in Antarctica into the Sinemurian.
Floral composition
Conifers
Conifer
Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
s formed a dominant component of Jurassic floras. The Late Triassic and Jurassic was a major time of diversification of conifers, with most modern conifer groups appearing in the fossil record by the end of the Jurassic, having evolved from voltzialean ancestors.
Araucarian conifers have their first unambiguous records during the Early Jurassic, and members of the modern genus ''Araucaria
''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen Conifer, coniferous trees in the family Araucariaceae. There are 20 extant taxon, extant species in New Caledonia (where 14 species are endemism, ende ...
'' were widespread across both hemispheres by the Middle Jurassic.
Also abundant during the Jurassic is the extinct family Cheirolepidiaceae
Cheirolepidiaceae is an extinct family of conifers. They first appeared in the Triassic, and were widespread during most of the Mesozoic era. They are united by the possession of a distinctive pollen type assigned to the form genus '' Classopolli ...
, often recognised through their highly distinctive '' Classopolis'' pollen. Jurassic representatives include the pollen cone '' Classostrobus'' and the seed cone '' Pararaucaria''. Araucarian and Cheirolepidiaceae conifers often occur in association.
The oldest definitive record of the cypress family (Cupressaceae
Cupressaceae is a conifer family, the cypress family, with worldwide distribution. The family includes 27–30 genera (17 monotypic), which include the junipers and redwoods, with about 130–140 species in total. They are monoecious, subdio ...
) is '' Austrohamia minuta'' from the Early Jurassic (Pliensbachian) of Patagonia, known from many parts of the plant. The reproductive structures of ''Austrohamia'' have strong similarities to those of the primitive living cypress genera ''Taiwania
''Taiwania'', with the single living species ''Taiwania cryptomerioides'', is a large coniferous tree in the cypress family Cupressaceae.
Etymology
''Taiwania'' means 'from Taiwan', while ''Cryptomerioides'' means 'resembling ''Cryptomeria''.G ...
'' and ''Cunninghamia
''Cunninghamia'' is a genus of one or two living species of evergreen coniferous trees in the cypress family Cupressaceae. They are native to China, northern Vietnam and Laos, and perhaps also Cambodia. They may reach in height. In vernacular ...
.'' By the Middle to Late Jurassic Cupressaceae were abundant in warm temperate–tropical regions of the Northern Hemisphere, most abundantly represented by the genus '' Elatides''.
Members of the extinct genus '' Schizolepidopsis'' which likely represent a stem-group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...
to the pine family (Pinaceae
The Pinaceae, or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as Cedrus, cedars, firs, Tsuga, hemlocks, larches, pines and spruces. The family is included in the order Pinales, ...
), were widely distributed across Eurasia during the Jurassic. The oldest unambiguous record of Pinaceae is the pine cone
A conifer cone (in formal botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers a ...
''Eathiestrobus
''Eathiestrobus mackenziei'' is a fossil pine cone found in the Kimmeridge Clay Formation (Upper Jurassic) near Eathie, on the Black Isle in Scotland. It is the oldest fossil pine currently known.
Etymology
The genus name ''Eathiestrobus'' refers ...
'', known from the Late Jurassic (Kimmeridgian) of Scotland, which remains the only known unequivocal fossil of the group before the Cretaceous. Despite being the earliest known member of the Pinaceae, ''Eathiestrobus'' appears to be a member of the pinoid clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
of the family, suggesting that the initial diversification of Pinaceae occurred earlier than has been found in the fossil record.
During the Early Jurassic, the flora of the mid-latitudes of Eastern Asia were dominated by the extinct deciduous broad leafed conifer ''Podozamites
''Podozamites'' is an extinct genus of fossil conifer leaves. In its broader sense, it has been used as a morphogenus (Form classification, form taxon) to refer to any broad leaved multi-veined conifer leaves. Modern broad-leaved conifers with a ...
,'' which appears to not be closely related to any living family of conifer. Its range extended northwards into polar latitudes of Siberia and then contracted northward in the Middle to Late Jurassic, corresponding to the increasing aridity of the region.
The earliest record of the yew family (Taxaceae
Taxaceae (), commonly called the yew family, is a coniferous family which includes six extant and two extinct genera, and about 30 species of plants, or in older interpretations three genera and 7 to 12 species.
Description
They are many-bran ...
) is '' Palaeotaxus rediviva'', from the Hettangian of Sweden, suggested to be closely related to the living ''Austrotaxus
''Austrotaxus spicata'', the New Caledonia yew or southern yew, is a species of yew, the sole species in the genus ''Austrotaxus''. It is related to the other yews in the genera ''Taxus'' and ''Pseudotaxus''.
It is endemic to New Caledonia, occ ...
'', while '' Marskea jurassica'' from the Middle Jurassic of Yorkshire, England and material from the Callovian–Oxfordian Daohugou Bed
The Haifanggou Formation (), also known as the Jiulongshan Formation (), is a fossil-bearing rock deposit located near Daohugou () village of Ningcheng County, in Inner Mongolia, northeastern China.
The formation consists of coarse conglomerates ...
in China are thought to be closely related to ''Amentotaxus
''Amentotaxus'' is a genus of conifers (catkin-yews) comprising five species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense. The genus is endemic to subtropical Southeast Asia, from Ta ...
,'' with the latter material assigned to the modern genus, indicating that Taxaceae had substantially diversified by the end of the Jurassic.
Podocarpaceae
Podocarpaceae is a large family of mainly Southern Hemisphere conifers, known in English as podocarps, comprising about 156 species of evergreen trees and shrubs.James E. Eckenwalder. 2009. ''Conifers of the World''. Portland, Oregon: Timber Pre ...
, today largely confined to the Southern Hemisphere, occurred in the Northern Hemisphere during the Jurassic, Examples include '' Podocarpophyllum'' from the Early to Middle Jurassic of Central Asia and Siberia, '' Scarburgia'' from the Middle Jurassic of Yorkshire, and '' Harrisiocarpus'' from the Jurassic of Poland.
Ginkgoales
Ginkgoales
Ginkgoales are a gymnosperm order containing only one extant species: ''Ginkgo biloba'', the ginkgo tree. It is monotypic, (the only taxon) within the class Ginkgoopsida, which itself is monotypic within the division Ginkgophyta . The order incl ...
, of which the sole living species is ''Ginkgo biloba
''Ginkgo biloba'', commonly known as ginkgo or gingko ( ), also known as the maidenhair tree, is a species of tree native to China. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossils ...
'', were more diverse during the Jurassic: they were among the most important components of Eurasian Jurassic floras and were adapted to a wide variety of climatic conditions. The earliest representatives of the genus ''Ginkgo
''Ginkgo'' is a genus of non-flowering seed plants. The scientific name is also used as the English name. The order to which it belongs, Ginkgoales, first appeared in the Permian, 270 million years ago, and is now the only living genus within ...
,'' represented by ovulate
Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilized ...
and pollen organs similar to those of the modern species, are known from the Middle Jurassic in the Northern Hemisphere. Several other lineages of ginkgoaleans are known from Jurassic rocks, including ''Yimaia
''Yimaia'' is a extinct genus of Ginkgoalean tree, and the only member of the family Yimaiaceae. In botanical form classification, its a form taxon for ginkgoalean ovulate organs. ''Yimaia'' species are distinguished from other Ginkgoales by ...
'', '' Grenana'', '' Nagrenia'' and ''Karkenia''. These lineages are associated with ''Ginkgo-''like leaves, but are distinguished from living and fossil representatives of ''Ginkgo'' by having differently arranged reproductive structures. '' Umaltolepis,'' historically thought to be ginkgoalean, and '' Vladimaria'' from the Jurassic of Asia have strap-shaped ginkgo-like leaves ('' Pseudotorellia'') with highly distinct reproductive structures with similarities to those of peltasperm and corystosperm seed ferns; these have been placed in the separate order Vladimariales, which may be related to Ginkgoales.
Bennettitales
Bennettitales
Bennettitales (also known as cycadeoids) is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales are among the most common Mesozoic seed plants ...
, having first become widespread during the preceding Triassic, were diverse and abundant members of Jurassic floras across both hemispheres. The foliage of Bennettitales bears strong similarities to those of cycads, to such a degree that they cannot be reliably distinguished on the basis of morphology alone. Leaves of Bennettitales can be distinguished from those of cycads their different arrangement of stoma
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...
ta, and the two groups are not thought to be closely related. Jurassic Bennettitales predominantly belong to the group Williamsoniaceae
''Williamsoniaceae'' is a family within the Bennettitales, an extinct group of seed plants within the Cycadophyta subdivision. Members of this family are believed to have been around two meters tall and with widely serrate leaves along a central ...
, which grew as shrubs and small trees. The Williamsoniaceae are thought to have had a divaricate
Divaricate means branching, or having separation or a degree of separation. The angle between branches is wide.
In botany
In botany, the term is often used to describe the branching pattern of plants. Plants are said to be divaricating when the ...
branching habit, similar to that of living ''Banksia
''Banksia'' is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and fruiting "cones" and heads. ''Banksias'' range i ...
'', and adapted to growing in open habitats with poor soil nutrient conditions. Bennettitales exhibit complex, flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
-like reproductive structures some of which are thought to have been pollinated by insects. Several groups of insects that bear long proboscis, including extinct families such as kalligrammatid
Kalligrammatidae, sometimes known as kalligrammatids or kalligrammatid lacewings, is a family of extinct insects in the order Neuroptera (lacewings) that contains twenty genera and a number of species. The family lived from the Middle Jurassic t ...
lacewings and extant ones such as acrocerid flies, are suggested to have been pollinators of bennettitales, feeding on nectar
Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...
produced by bennettitalean cones.
Cycads
Cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants o ...
s reached their apex of diversity during the Jurassic and Cretaceous Periods. Despite the Mesozoic sometimes being called the "Age of Cycads", cycads are thought to have been a relatively minor component of mid-Mesozoic floras, with the Bennettitales and Nilssoniales
''Nilssonia'' is a genus of fossil foliage traditionally assigned to the Cycadophyta either in Cycadales or their own order Nilssoniales, though the relationships of this genus with the Cycadales have been put into question on chemical grounds.
...
, which have cycad-like foliage, being dominant. The Nilssoniales have often been considered cycads or cycad relatives, but have been found to be distinct on chemical grounds, and perhaps more closely allied with Bennettitales.'''' Cycads are thought to have been mostly confined to tropical and subtropical latitudes throughout their evolutionary history. The relationships of most Mesozoic cycads to living groups are ambiguous. Modern cycads are pollinated by beetles, and such an association is thought to have formed by the Early Jurassic.
Other seed plants
Although there have been several claimed records and phylogenetic stem group age estimates for individual early diverging angiosperm orders, there are no widely accepted Jurassic fossil records of flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s, which make up 90% of living plant species, and fossil evidence suggests that the group diversified during the following Cretaceous.
The earliest known Gnetophytes
Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three rel ...
appeared by the end of the Jurassic.
"Seed ferns" (Pteridospermatophyta
The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic group of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late Devonian ...
) is a collective term to refer to disparate lineages of fern like plants that produce seeds but have uncertain affinities to living seed plant
A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. Spermatophytes are a subset of the embryophytes or land plants. They inc ...
groups. A prominent group of Jurassic seed ferns is the Caytoniales
The Caytoniales (Figs. 1-2) are an extinct order of seed plants known from fossils collected throughout the Mesozoic Era, around . They are regarded as seed ferns because they are seed-bearing plants with fern-like leaves. Although at one time ...
, which reached their zenith during the Jurassic, with widespread records in the Northern Hemisphere, though records in the Southern Hemisphere remain rare. Due to their berry
A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...
-like seed-bearing capsules, they have often been suggested to have been closely related or perhaps ancestral to flowering plants, but the evidence for this is inconclusive. A variety of other Jurassic seed ferns of uncertain placement are known, including ''Pachypteris
''Pachypteris'' ( Brongn.) T.M.Harris. is a Mesozoic pteridosperm leaf fossil probably belonging to the seed fern Order Peltaspermales.
Description
''Pachypteris'' is represented by hypostomatic, bipinnate or unipinnate leaves, with alethopte ...
'' from Europe, which has sometimes been allied with the corystosperms.
Czekanowskiales, also known as Leptostrobales, are a group of seed plants uncertain affinities with persistent heavily dissected leaves borne on deciduous short shoots, subtended by scale-like leaves, known from the Late Triassic (possibly Late Permian) to Cretaceous. They are thought to have had a tree- or shrub-like habit and formed a conspicuous component of Northern Hemisphere Mesozoic temperate and warm-temperate floras. The genus '' Phoenicopsis'' was widespread in Early-Middle Jurassic floras of Eastern Asia and Siberia.
The Pentoxylales
Pentoxylales is an extinct order of seed plants known from the Jurassic and Early Cretaceous of East Gondwana.
Discovery
The first specimens belonging to Pentoxylales were reported by Birbal Sahni in 1948 from Jurassic-Cretaceous strata of t ...
, a small but clearly distinct group of liana
A liana is a long- stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word ''liana'' does not refer to a ta ...
-like seed plants of obscure affinities, first appeared during the Jurassic. Their distribution appears to have been confined to Eastern Gondwana.
Ferns and allies
Living families of ferns widespread during the Jurassic include Dipteridaceae
The Dipteridaceae is a family (biology), family of ferns in the order Gleicheniales of the class Polypodiopsida. They are commonly known as umbrella ferns and contain two genera, ''Cheiropleuria'' and ''Dipteris'', with a total of nine species c ...
, Matoniaceae
Matoniaceae is one of the three families of ferns in the Gleicheniales order of the Polypodiopsida class. Fossil records reveal that Matoniaceae ferns were abundant during the Mesozoic era (about 250-million to 66-million years ago), during which ...
, Gleicheniaceae
The forked ferns are the family Gleicheniaceae, which includes six genera and about 160 known species. The formerly independent families Dicranopteridaceae and Stromatopteridaceae are generally included in the Gleicheniaceae, whereas the Dipteri ...
, Osmundaceae
Osmundaceae (royal fern family) is a family of ferns containing four to six extant genera and 18–25 known species. It is the only living family of the order Osmundales in the class Polypodiopsida (ferns) or in some classifications the only ord ...
and Marattiaceae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
. Polypodiales
The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas.
Description
Polypodiale ...
, which make up 80% of living fern diversity, have no record from the Jurassic and are thought to have diversified in the Cretaceous, though the widespread Jurassic herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of t ...
fern genus ''Coniopteris
''Coniopteris'' is an extinct genus of Mesozoic fern leaves with a fossil range from the Early Jurassic to the Cenomanian stage of the Late Cretaceous. It was widespread over both hemispheres during the Jurassic and Early Cretaceous, with over 13 ...
,'' historically interpreted as a close relative of tree fern
The tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tree ...
s of the family Dicksoniaceae
Dicksoniaceae is a group of tropical, subtropical and warm temperate ferns, treated as a family in the Pteridophyte Phylogeny Group classification of 2016 (PPG I), and counting 30-40 species. Alternatively, the family may be sunk into a very broa ...
, has recently been reinterpreted as an early relative of the group.
The Cyatheales
The order Cyatheales, which includes most tree ferns, is a taxonomic order of the fern class, Polypodiopsida. No clear morphological features characterize all of the Cyatheales, but DNA sequence data indicate the order is monophyletic. Some sp ...
, the group containing most modern tree ferns, appeared during the Late Jurassic, represented by members of the genus '' Cyathocaulis'', which are suggested to be early members of Cyatheaceae
The Cyatheaceae are a family of ferns, the scaly tree ferns, one of eight families in the order Cyatheales in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the family may defined much more broadly (Cyatheaceae '' ...
on the basis of cladistic analysis. Only a handful of possible records exist of the Hymenophyllaceae
The Hymenophyllaceae, the filmy ferns and bristle ferns, are a family of two to nine genera (depending on classification system) and about 650 known species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp pla ...
from the Jurassic, including ''Hymenophyllites macrosporangiatus'' from the Russian Jurassic.
The oldest remains of modern horsetails
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass Eq ...
of the genus ''Equisetum
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass Eq ...
'' first appear in the Early Jurassic, represented by '' Equisetum dimorphum'' from the Early Jurassic of Patagonia and ''Equisetum laterale
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass E ...
'' from the Early to Middle Jurassic of Australia. Silicified
In geology, petrifaction or petrification () is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals. Petrified wood typifies this proce ...
remains of ''Equisetum thermale
''Equisetum thermale'' is an extinct horsetail species in the family Equisetaceae described from a group of whole plant fossils including rhizomes, stems, and leaves. The species is known from Middle to Late Jurassic sediments exposed in the p ...
'' from the Late Jurassic of Argentina exhibit all the morphological characters of modern members of the genus. The estimated split between ''Equisetum bogotense
''Equisetum bogotense'', the Andean horsetail, is a herbaceous perennial that reproduces through spores. It has thicker less bushy whorled branches, and a silica rich rhizomatous stem, which roots grow out of, under ground. This stem is a dull ...
'' and all other living ''Equisetum'' is estimated to have occurred no later than the Early Jurassic.
Lower plants
Quillworts virtually identical to modern species are known from the Jurassic onwards. '' Isoetites rolandii'' from the Middle Jurassic of Oregon is the earliest known species to represent all major morphological features of modern ''Isoetes''. More primitive forms such as '' Nathorstiana,'' which retain an elongated stem, persisted into the Early Cretaceous.
The moss '' Kulindobryum'' from the Middle Jurassic of Russia, which was found associated with dinosaur bones, is thought to be related to the Splachnaceae
Splachnaceae is a family of mosses, containing around 70 species in 6 genera. Around half of those species are entomophilous, using insects to disperse their spores, a characteristic found in no other seedless land plants.
Many species in this f ...
, which grow on animal caracasses. '' Bryokhutuliinia'' from the same region is thought to be related to Dicranales
Dicranales is an order of haplolepideous mosses in the subclass Dicranidae
The Dicranidae are a widespread and diverse subclass of mosses in class Bryopsida, with many species of dry or disturbed areas. They are distinguished by their spore
...
. '' Heinrichsiella'' from the Jurassic of Patagonia is thought to belong to either Polytrichaceae
Polytrichaceae is a common family of mosses. Members of this family tend to be larger than other mosses with a thickened central stem and a rhizome. The leaves have a midrib that bears photosynthetic lamellae on the upper surface. Species in ...
or Timmiellaceae
Timmiellaceae is a family of haplolepideous mosses (Dicranidae). It contains two genera, '' Luisierella'' and '' Timmiella'', that were formerly place in family Pottiaceae.
Taxonomy
The genera ''Luisierella'' and ''Timmiella'' have been trad ...
.
The liverwort '' Pellites hamiensis'' from the Middle Jurassic Xishanyao Formation of China is the oldest record of the family Pelliaceae
Pelliaceae is a family of liverworts which has included three genera: '' Pellia'' (in the temperate Northern Hemisphere) and '' Noteroclada'' (in the Southern Hemisphere), and '' Androcryphia''. The three genera are easily distinguished, not on ...
. ''Pallaviciniites sandaolingensis'' from the same deposit is thought to belong to the subclass Pallaviciniineae within the Pallaviciniales
Pallaviciniales is an order of liverworts.
Taxonomy
* Pallaviciniineae Schuster 1984
** Hymenophytaceae Schuster 1963
*** ''Hymenophyton'' Dumortier 1835 Umbraculum'' Gottsche 1861 non Schumacher 1817 non Kuntze 1891]
** Moerckiaceae Stotler ...
. '' Ricciopsis, Ricciopsis sandaolingensis'', also from the same deposit, is the only Jurassic record of Ricciaceae
Ricciaceae are a family of liverworts in order Marchantiales, with two extant genera.
* ''Riccia
''Riccia'' is a genus of liverworts in the order Marchantiales.
These plants are small and thalloid, that is not differentiated into root, stem ...
.
Fauna
Reptiles
Crocodylomorphs
The Triassic–Jurassic extinction decimated pseudosuchia
Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...
n diversity, with crocodylomorphs
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction.
During Mesozoic and early Cenozoic times, cr ...
, which originated during the early Late Triassic, being the only group of pseudosuchians to survive, with all others, including the herbivorous aetosaur
Aetosaurs () are heavily armored reptiles belonging to the extinct order Aetosauria (; from Greek, (aetos, "eagle") and (, "lizard")). They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs ...
s and carnivorous "rauisuchians
"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians t ...
" becoming extinct. The morphological diversity of crocodylomorphs during the Early Jurassic was around the same as those of Late Triassic pseudosuchians, but they occupied different areas of morphospace, suggesting that they occupied different ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
s to their Triassic counterparts and that there was an extensive and rapid radiation of crocodylomorphs during this interval. While living crocodilia
Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...
ns are confined to an aquatic ambush predator lifestyle, Jurassic crocodylomorphs exhibited a wide variety of life habits. An unnamed protosuchid
Protosuchidae was a family of crocodylomorph reptiles from the Late Triassic, Jurassic, and Cretaceous time periods. They were closely related to the Gobiosuchidae.
Distribution
Triassic protosuchids are known from Lesotho, Argentina, and Arizon ...
known from teeth from the Early Jurassic of Arizona represents the earliest known herbivorous crocodylomorph, an adaptation that appeared several times during the Mesozoic.
The Thalattosuchia
Thalattosuchia is a clade of marine crocodylomorphs from the Early Jurassic to the Early Cretaceous that had a cosmopolitan distribution. They are colloquially referred to as marine crocodiles or sea crocodiles, though they are not members of Cro ...
, a clade of predominantly marine crocodylomorphs, first appeared during the Early Jurassic and became a prominent part of marine ecosystems. Within Thalattosuchia, the Metriorhynchidae became highly adapted for life in the open ocean, including the transformation of limbs into flippers, the development of a tail fluke, and smooth, scaleless skin. The morphological diversity of crocodylomorphs during the Early and Middle Jurassic was relatively low compared to that in later time periods and was dominated by terrestrial small-bodied, long-legged sphenosuchia
Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, ...
ns, early crocodyliforms
Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...
and thalattosuchians. The Neosuchia
Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to ''Crocodylus niloticus' ...
, a major group of crocodylomorphs, first appeared during the Early to Middle Jurassic. The Neosuchia represents the transition from an ancestrally terrestrial lifestyle to a freshwater aquatic ecology similar to that occupied by modern crocodilians. The timing of the origin of Neosuchia is disputed. The oldest record of Neosuchians has been suggested to be ''Calsoyasuchus
''Calsoyasuchus'' (meaning " r. KyrilCalsoyas' crocodile") is a genus of crocodylomorph that lived in the Early Jurassic. Its fossilized remains were found in the Sinemurian-Pliensbachian-age Kayenta Formation on Navajo Nation land in Coconino ...
,'' from the Early Jurassic of Arizona, which in many analyses has been recovered as the earliest branching member of the neosuchian family Goniopholididae
Goniopholididae is an extinct family of moderate-sized semi-aquatic neosuchian crocodyliformes. Their bodyplan and morphology are convergent on living crocodilians. They lived across Laurasia (Asia, Europe and North America) between the Middle J ...
, which radically alters times of diversification for crocodylomorphs. However, this placement has been disputed, with some analyses finding it outside Neosuchia, which would place the oldest records of Neosuchia in the Middle Jurassic. ''Razanandrongobe
''Razanandrongobe'' (meaning "ancestor f thelarge lizard" in Malagasy) is a genus of carnivorous ziphosuchian crocodyliform from the Middle Jurassic of Madagascar. It contains the type and only species ''Razanandrongobe sakalavae'', named in 2 ...
'' from the Middle Jurassic of Madagascar has been suggested the represent the oldest record of Notosuchia
Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebecosu ...
, a primarily Gondwanan clade of mostly terrestrial crocodylomorphs, otherwise known from the Cretaceous and Cenozoic.
Turtles
Stem-group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...
turtles (Testudinata
Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Jacob The ...
) diversified during the Jurassic. Jurassic stem-turtles belong to two progressively more advanced clades, the Mesochelydia
Mesochelydia (from Greek ''mesos'' "middle" and ''chelys'' "turtle") is a clade within Pantestudines, more inclusive than Perichelydia, but less than Testudinata. The clade is known from the Early Jurassic to the Present, and contains all Jurass ...
and Perichelydia
Perichelydia (from Greek ''peri'' "near" and ''chelys'' "turtle") is a clade within Pantestudines (turtles and their extinct relatives) known from the Middle Jurassic to Holocene. Alongside crown group Testudines, it also contains Helochelydrid ...
. It is thought that the ancestral condition for mesochelydians is aquatic, as opposed to terrestrial for testudinates. The two modern groups of turtles (Testudines
Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...
), Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differen ...
and Cryptodira
The Cryptodira ('' el, hidden neck'') are a suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira (side-necked turtles) in that they lower their necks and pull the heads straight back into the ...
, diverged by the beginning of the Late Jurassic. The oldest known pleurodires, the Platychelyidae
Platychelyidae is an extinct family of pan-pleurodiran turtles, known from the Late Jurassic and Early Cretaceous of Europe, South America, North America, and the Caribbean. It represents the oldest known clade of stem-pleurodires. All known memb ...
, are known from the Late Jurassic of Europe and the Americas, while the oldest unambiguous cryptodire, ''Sinaspideretes
''Sinaspideretes'' is an extinct genus of turtle from the Late Jurassic of China, probably from the Shaximiao Formation. It is considered the earliest and most basal representative of the Trionychia, and is possibly the oldest known member of C ...
,'' an early relative of softshell turtles, is known from the Late Jurassic of China. The Thalassochelydia
Thalassochelydia is a clade of extinct marine turtles from the Late Jurassic and earliest Cretaceous of Europe and South America. The group is defined as including ''Eurysternum'', ''Plesiochelys'' and ''Thalassemys'' to the exclusion of ''Pelome ...
, a diverse lineage of marine turtles unrelated to modern sea turtles
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, ...
, are known from the Late Jurassic of Europe and South America.
Lepidosaurs
Rhynchocephalia
Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse g ...
ns (the sole living representative being the tuatara
Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...
) had achieved a global distribution by the beginning of the Jurassic. Rhynchocephalians reached their highest morphological diversity in their evolutionary history during the Jurassic, occupying a wide range of lifestyles, including the aquatic pleurosaurs with long snake-like bodies and reduced limbs, the specialized herbivorous eilenodontines, as well as ''Oenosaurus
''Oenosaurus'' is an extinct genus of sphenodontian reptile from the Late Jurassic (Tithonian) aged Mörnsheim Formation of Germany.
Description
The genus is known from a partial skull preserved in ventral view.
Diet and lifestyle
It is like ...
,'' which had broad tooth plates indicative of durophagy
Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil tu ...
. Rhynchocephalians disappeared from Asia after the Early Jurassic. The last common ancestor of living squamates
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, i ...
(which includes lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
s and snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
s) is estimated to have lived around 190 million years ago during the Early Jurassic, with the major divergences between modern squamate lineages estimated to have occurred during the Early to Middle Jurassic. Squamates first appear in the fossil record during the Middle Jurassic including members of modern clades such as Scincomorpha
Scincomorpha is an infraorder and clade of lizards including skinks (Scincidae) and their close relatives. These include the living families Cordylidae (girdled lizards), Gerrhosauridae (plated lizards), and Xantusiidae (night lizards), as well ...
, though many Jurassic squamates have unclear relationships to living groups. ''Eichstaettisaurus
''Eichstaettisaurus'' (meaning "Eichstätt lizard") is a genus of lizards from the Late Jurassic and Early Cretaceous of Germany, Spain, and Italy. With a flattened head, forward-oriented and partially symmetrical feet, and tall claws, ''Eichstae ...
'' from the Late Jurassic of Germany has been suggested to be an early relative of gecko
Geckos are small, mostly carnivorous lizards that have a wide distribution, found on every continent except Antarctica. Belonging to the infraorder Gekkota, geckos are found in warm climates throughout the world. They range from .
Geckos ar ...
s and displays adaptations for climbing. ''Dorsetisaurus
''Dorsetisaurus'' is a genus of extinct lizard, known from the Late Jurassic of North America, and the Late Jurassic-earliest Cretaceous of Europe. The genus was first reported from the Early Cretaceous (Berriasian) Lulworth Formation of the Pur ...
'' from the Late Jurassic of North America and Europe represents the oldest widely accepted record of Anguimorpha
The Anguimorpha is a suborder of squamates. The group was named by Fürbringer in 1900 to include all autarchoglossans closer to '' Varanus'' and '' Anguis'' than ''Scincus
''Scincus'' is a genus of skinks, lizards in the family Scincidae. Th ...
. ''Tamaulipasaurus
''Tamaulipasaurus'' is an extinct genus of lepidosauromorph reptile from the Early Jurassic of Mexico. It contains a single species, ''Tamaulipasaurus morenoi'', which is based on skull material found at Huizachal Canyon, a productive fossil sit ...
'' from Early Jurassic of Mexico and ''Marmoretta
''Marmoretta'' is an extinct genus of small lepidosauromorph reptile known from the Middle Jurassic (late Bathonian age) of Oxfordshire, England and Skye, Scotland. It contains a single species, ''Marmoretta oxoniensis''.
Etymology
''Marmoretta ...
'' from the Middle Jurassic of Britain represents late surviving lepidosauromorphs outside both Rhynchocephalia and Squamata.
File:Vadasaurus herzogi holotype (fossil).jpg, '' Vadasaurus herzogi'', a rynchocephalian from the Upper Jurassic Solnhofen Limestone of Germany
File:Homeosaurus maximiliani, lizard, Jurassic, Solnhofen Limestone, Eichstatt, Bavaria, Germany - Houston Museum of Natural Science - DSC01988.JPG, '' Homeosaurus maximiliani'', a rynchocephalian from the Solnhofen Limestone
File:Pleurosaurus 783534.jpg, ''Pleurosaurus
''Pleurosaurus'' (meaning "side lizard") is an extinct genus of diapsid reptiles belonging to the group Sphenodontia, extinct relatives of the modern tuatara. ''Pleurosaurus'' fossils were discovered in the Solnhofen Limestone of Bavaria, Germ ...
,'', an aquatic rhynchocephalian from the Late Jurassic of Europe
File:Eichstaettisaurus schroederi.JPG, '' Eichstaettisaurus schroederi,'', an extinct lizard from the Solnhofen Limestone
Choristoderes
The earliest known remains of Choristodera, a group of freshwater aquatic reptiles with uncertain affinities to other reptile groups, are found in the Middle Jurassic. Only two genera of choristodere are known from the Jurassic. One is the small lizard-like ''Cteniogenys
''Cteniogenys'' is a genus of choristodere, a morphologically diverse group of aquatic reptiles. It is part of the monotypic family Cteniogenidae. The type and only named species, ''C. antiquus'', was named in 1928 by Charles W. Gilmore. The ho ...
'', thought to be the most basal known choristodere; it is known from the Middle to Late Jurassic of Europe and Late Jurassic of North America, with similar remains also known from the upper Middle Jurassic of Kyrgyzstan and western Siberia. The other is ''Coeruleodraco
''Coeruleodraco'' is an extinct genus of choristoderan known from the Late Jurassic ( Oxfordian) Tiaojishan Formation in China. ''Coeruleodraco'' is significant as the most complete Jurassic choristodere taxon, as the only other named Jurassic c ...
'' from the Late Jurassic of China, which is a more advanced choristodere, though still small and lizard-like in morphology.
Ichthyosaurs
Ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s suffered an evolutionary bottleneck
A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as specicide, widespread violen ...
during the end-Triassic extinction, with all non-neoichthyosauria
Parvipelvia (Latin for "little pelvis" - ''parvus'' meaning "little" and ''pelvis'' meaning "pelvis") is an extinct clade of euichthyosaur ichthyosaurs that existed from the Late Triassic to the early Late Cretaceous (middle Norian to Cenom ...
ns becoming extinct. Ichthyosaurs reached their apex of species diversity during the Early Jurassic, with an array of morphologies including the huge apex predator
An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own.
Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...
''Temnodontosaurus
''Temnodontosaurus'' (Greek for "cutting-tooth lizard"temno, meaning "to cut", odont meaning "tooth" and sauros meaning "lizard") is an extinct genus of ichthyosaur from the Early Jurassic period. They lived between 200 and 175 million years ag ...
'' and swordfish-like ''Eurhinosaurus
''Eurhinosaurus'' (Greek for 'well-nosed lizard'- eu meaning 'well or good', rhino meaning 'nose' and sauros meaning 'lizard') is an extinct genus of ichthyosaur from the Early Jurassic (Toarcian), ranging between 183 and 175 million years. Foss ...
,'' though Early Jurassic ichthyosaurs were significantly less morphologically diverse than their Triassic counterparts. At the Early–Middle Jurassic boundary, between the end of the Toarcian and the beginning of the Bajocian, most lineages of ichythosaur appear to have become extinct, with the first appearance of the Ophthalmosauridae
Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous (Bajocian - Cenomanian) worldwide. Almost all ichthyosaurs from the Middle Jurassic onwards belong to the family, until the ex ...
, the clade that would encompass almost all ichthyosaurs from then on, during the early Bajocian. Ophthalmosaurids were diverse by the Late Jurassic, but failed to fill many of the niches that had been occupied by ichthyosaurs during the Early Jurassic.
Plesiosaurs
Plesiosaurs
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia.
Plesiosaurs first appeared ...
originated at the end of the Triassic (Rhaetian). By the end of the Triassic, all other sauropterygia
Sauropterygia ("lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became ...
ns, including placodonts
Placodonts ("Tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally ...
and nothosaur
Nothosaurs (order Nothosauroidea) were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail.F. v. ...
s, had become extinct. At least six lineages of plesiosaur crossed the Triassic–Jurassic boundary. Plesiosaurs were already diverse in the earliest Jurassic, with the majority of plesiosaurs in the Hettangian-aged Blue Lias belonging to the Rhomaleosauridae
Rhomaleosauridae is a family of plesiosaurs from the Earliest Jurassic to the latest Middle Jurassic (Hettangian to Callovian stages) of Europe, North America, South America and possibly Asia. Most rhomaleosaurids are known from England, many sp ...
. Early plesiosaurs were generally small-bodied, with body size increasing into the Toarcian. There appears to have been a strong turnover around the Early–Middle Jurassic boundary, with microcleidids and rhomaleosaurids becoming extinct and nearly extinct respectively after the end of the Toarcian with the first appearance of the dominant clade of plesiosaurs of the latter half of the Jurassic, the Cryptoclididae
Cryptoclididae is a family (biology), family of medium-sized plesiosaurs that existed from the Middle Jurassic to the Early Cretaceous. They had long necks, broad and short skulls and densely packed teeth. They fed on small soft-bodied preys such ...
during the Bajocian. The Middle Jurassic saw the evolution of short-necked and large-headed thalassophonean pliosaurs from ancestrally small-headed, long-necked forms''.'' Some thalassophonean pliosaurs, such as some species of ''Pliosaurus
''Pliosaurus'' (meaning 'more lizard') is an extinct genus of thalassophonean pliosaurid known from the Kimmeridgian and Tithonian stages (Late Jurassic) of Europe and South America. Their diet would have included fish, cephalopods, and marine re ...
'', had skulls up to two metres in length with body lengths estimated around 10–12 metres, making them the apex predators of Late Jurassic oceans. Plesiosaurs invaded freshwater environments during the Jurassic, with indeterminate remains of small-bodied pleisosaurs known from freshwater sediments from the Jurassic of China and Australia.
Pterosaurs
Pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
s first appeared in the Late Triassic. A major radiation of Jurassic pterosaurs is the Rhamphorhynchidae
Rhamphorhynchidae is a group of early pterosaurs named after ''Rhamphorhynchus'', that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.Seeley, H.G. (1870). "The Orithosauria: An Elementary Study o ...
, which first appeared in the late Early Jurassic (Toarcian); they are thought to been piscivorous
A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...
. Anurognathids, which first appeared in the Middle Jurassic, possessed short heads and densely furred bodies, and are thought to have been insectivores. Derived monofenestrata
Monofenestrata is an unranked group of pterosaurs that includes the family Wukongopteridae and the suborder Pterodactyloidea.
The clade Monofenestrata was in 2009/2010 defined as the group consisting of ''Pterodactylus'' and all species sharing ...
n pterosaurs such as wukongopterids appeared in the late Middle Jurassic. Advanced short-tailed pterodactyloids
Pterodactyloidea (derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger" meaning "winged finger", "wing-finger" or "finger-wing") is one of the two traditional ...
first appeared at the Middle–Late Jurassic boundary. Jurassic pterodactyloids include the ctenochasmatids, like ''Ctenochasma
''Ctenochasma'' (meaning "comb jaw") is a genus of Late Jurassic ctenochasmatid pterosaur belonging to the suborder Pterodactyloidea. Three species are currently recognized: ''C. roemeri'' (named after Friedrich Adolph Roemer), ''C. taqueti'', a ...
'', which have closely spaced needle-like teeth that were presumably used for filter feeding
Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
. The bizarre Late Jurassic ctenochasmatoid ''Cycnorhamphus
''Cycnorhamphus'' (meaning "swan beak") is a genus of gallodactylid ctenochasmatoid pterosaur from the Late Jurassic period of France and Germany, about 152 million years ago. It is probably synonymous with the genus ''Gallodactylus''.
History ...
'' had a jaw with teeth only at the tips, with bent jaws like those of living openbill stork
The openbill storks or openbills are two species of stork (family (biology), family ''Ciconiidae'') in the genus ''Anastomus''. They are large wading birds characterized by large bills, the mandibles of which do not meet except at the tip. This f ...
s that may have been used to hold and crush hard invertebrates.
Dinosaurs
Dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s, which had morphologically diversified in the Late Triassic, experienced a major increase in diversity and abundance during the Early Jurassic in the aftermath of the end-Triassic extinction and the extinction of other reptile groups, becoming the dominant vertebrates in terrestrial ecosystems. ''Chilesaurus
''Chilesaurus'' is an extinct genus of herbivorous dinosaur. The type and only known species so far is ''Chilesaurus diegosuarezi''. ''Chilesaurus'' lived about 145 million years ago (Mya) in the Late Jurassic period of Chile. Showing a combinat ...
'', a morphologically aberrant herbivorous dinosaur from the Late Jurassic of South America, has uncertain relationships to the three main groups of dinosaurs, having been recovered as a member of all three in different analyses.
Theropods
Advanced theropods
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ca ...
belonging to Neotheropoda
Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and is the only group of theropods that survived the Triassic–Jurassic extinction event. All neotheropods became extinct by the ...
first appeared in the Late Triassic. Basal neotheropods, such as coelophysoids
Coelophysoidea were common dinosaurs of the Late Triassic and Early Jurassic periods. They were widespread geographically, probably living on all continents. Coelophysoids were all slender, carnivorous forms with a superficial similarity to the ...
and dilophosaurs, persisted into the Early Jurassic, but became extinct by the Middle Jurassic. The earliest averostra
Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs, namely Ceratosauria and Tetanurae, and represent the only group of post-Early Jurassic theropods. Both survived into the Cretaceous period. When the Cretaceous–Pa ...
ns appear during the Early Jurassic, with the earliest known member of Ceratosauria
Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with ''Ceratosaurus'' than with birds. The oldest known ceratosaur, ''Saltriovenator'', dates to the earliest ...
being ''Saltriovenator
''Saltriovenator'' (meaning "Saltrio hunter") is a genus of ceratosaurian dinosaur that lived during the Sinemurian stage of the Early Jurassic in what is now Italy. The type and only species is ''Saltriovenator zanellai''; in the past, the sp ...
'' from the early Sinemurian (199.3–197.5 million years ago) of Italy. The unusual ceratosaur ''Limusaurus
''Limusaurus'' is a genus of theropod dinosaur that lived in what is now China during the Late Jurassic, around 161 to 157 million years ago. The type and only species ''Limusaurus inextricabilis'' was described in 2009 from specimens ...
'' from the Late Jurassic of China had a herbivorous diet, with adults having edentulous
Toothlessness, or edentulism, is the condition of having no teeth. In organisms that naturally have teeth, it is the result of tooth loss.
Organisms that never possessed teeth can also be described as edentulous. Examples are the members of the ...
beaked jaws, making it the earliest known theropod to have converted from an ancestrally carnivorous diet. The earliest members of the Tetanurae
Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans (including birds). Tetanurans are ...
appeared during the late Early Jurassic or early Middle Jurassic. The Megalosauridae
Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. They were a relatively ...
represent the oldest radiation of the Tetanurae, first appearing in Europe during the Bajocian. The oldest member of Allosauroidea
Allosauroidea is a superfamily or clade of theropod dinosaurs which contains four family (biology), families — the Metriacanthosauridae, Allosauridae, Carcharodontosauridae, and Neovenatoridae. Allosauroids, alongside the family Megalosauroid ...
has been suggested to be ''Asfaltovenator
''Asfaltovenator'' (meaning "Cañadón Asfalto Formation hunter" after the fossil formation in which its fossils were found) is a genus of possibly allosauroid dinosaur from the Lower Jurassic Cañadón Asfalto Formation from Chubut Province, Arge ...
'' from the Middle Jurassic of South America. Coelurosaurs
Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.
Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrann ...
first appeared during the Middle Jurassic, including early tyrannosaurs
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent be ...
such as ''Proceratosaurus
''Proceratosaurus'' is a genus of carnivore, carnivorous theropod dinosaur from the Middle Jurassic (Bathonian) of England. ''Proceratosaurus'' was a small dinosaur, measuring in length and in body mass.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: ...
'' from the Bathonian of Britain. Some coelurosaurs from the Late Jurassic of China including ''Shishugounykus
''Shishugounykus'' (meaning "Shishugou claw" after the Shishugou Formation where it was found) is a genus of basal alvarezsaurian dinosaur from the Shishugou Formation from Xinjiang in China
China, officially the People's Republic of Ch ...
'' and ''Haplocheirus
''Haplocheirus'' is a genus of theropod dinosaur. Upon its description, it was considered the oldest alvarezsauroid, predating all other members by about 63 million years. This has subsequently been questioned. A 2019 study considered ''Haploch ...
'' are suggested to represent early alvarezsaurs
Alvarezsauroidea is a group of small maniraptoran dinosaurs. Alvarezsauroidea, Alvarezsauridae, and Alvarezsauria are named for the historian Gregorio Álvarez (historian), Gregorio Álvarez, not the more familiar physicist Luis Walter Alvarez, L ...
, however, this has been questioned. Scansoriopterygids, a group of small feathered coelurosaurs with membraneous, bat-like wings for gliding, are known from the Middle to Late Jurassic of China. The oldest record of troodontids
Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discov ...
is suggested to be ''Hesperornithoides
''Hesperornithoides'' (meaning "western bird form"; nicknamed "Lori") is a genus of troodontid theropod dinosaur that lived in North America during the Late Jurassic period.
Discovery
Although several Troodontid teeth were found, with the trood ...
'' from the Late Jurassic of North America. Tooth remains suggested to represent those of dromaeosaurs
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...
are known from the Jurassic, but no body remains are known until the Cretaceous.
File:Ceratosaurus mounted white background.jpg, Skeleton of ''Ceratosaurus
''Ceratosaurus'' (from Ancient Greek, Greek κέρας/κέρατος, ' meaning "horn" and wikt:σαῦρος, σαῦρος ' meaning "lizard") was a carnivorous Theropoda, theropod dinosaur in the Late Jurassic Period (geology), period (Kim ...
'', a ceratosaurid from the Late Jurassic of North America
File:Monolophosaurus jiangi.jpg, Skeleton of ''Monolophosaurus
''Monolophosaurus'' ( ; meaning "single-crested lizard") is an extinct genus of tetanuran theropod dinosaur from the Middle Jurassic Shishugou Formation in what is now Xinjiang, China.Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up ...
'', a basal tetanuran from the Middle Jurassic of China
File:Yi qi restoration.jpg, Restoration of '' Yi qi'', a scansoriopterygid from the Middle to Late Jurassic of China
= Birds
=
The earliest avialans
Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally use ...
, which include birds and their ancestors, appear during the Middle to Late Jurassic, definitively represented by ''Archaeopteryx
''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird''), is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaīos''), meaning "ancient", and (''ptéryx''), meaning "feather" ...
'' from the Late Jurassic of Germany. Avialans belong to the clade Paraves
Paraves are a widespread group of theropod dinosaurs that originated in the Middle Jurassic period. In addition to the extinct dromaeosaurids, troodontids, anchiornithids, and possibly the scansoriopterygids, the group also contains the avial ...
within Coelurosauria, which also includes dromaeosaurs and troodontids. The Anchiornithidae
Anchiornithidae ("near birds") is a family of eumaniraptorans which could be the basalmost family of birds (in the general sense) in the clade Avialae. Anchiornithids have been classified at varying positions in the maniraptoran tree, with some ...
from the Middle-Late Jurassic of Eurasia have frequently suggested to be avialans, but have also alternatively found as a separate lineage of paravians.
Ornithischians
The earliest definitive ornithischia
Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek s ...
ns appear during the Early Jurassic, represented by basal ornithischians like ''Lesothosaurus
''Lesothosaurus'' is a monospecific genus of ornithischian dinosaur that lived during the Early Jurassic in what is now South Africa and Lesotho. It was named by paleontologist Peter Galton in 1978, the name meaning " lizard from Lesotho". The g ...
'', heterodontosaurids, and early members of Thyreophora
Thyreophora ("shield bearers", often known simply as "armored dinosaurs") is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous.
Thyreophorans are characterized by the presence of body ...
. The earliest members of Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. ...
and Stegosauria
Stegosauria is a group of herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere, predominantly in what is now North America, Europe, ...
appear during the Middle Jurassic. The basal neornithischia
Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. It is the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside ...
n ''Kulindadromeus
''Kulindadromeus'' was a herbivorous dinosaur, a basal neornithischian from the Middle Jurassic. The first ''Kulindadromeus'' fossil was found in Russia. Its feather-like integument is evidence for protofeathers being basal to Ornithischia and ...
'' from the Middle Jurassic of Russia indicates that at least some ornithischians were covered in protofeathers
A feathered dinosaur is any species of dinosaur possessing feathers. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form.
It has been su ...
. The earliest members of Ankylopollexia
Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna. The name stems from the Greek wor ...
, which become prominent in the Cretaceous, appeared during the Late Jurassic, represented by bipedal forms such as ''Camptosaurus
''Camptosaurus'' ( ) is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America and possibly also Europe. The name means 'flexible lizard' (Greek (') meaning 'bent' and (') meaning 'lizard') ...
''. Ceratopsia
Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. ...
ns first appeared in the Late Jurassic of China, represented by members of Chaoyangsauridae
Chaoyangsauridae is a family (biology), family of ceratopsian dinosaurs. They are among the earliest known marginocephalian dinosaurs, with remains dating to about 160 million years ago, during the Late Jurassic period. Members of this group had ...
.
Sauropodomorphs
Sauropods
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
became the dominant large herbivores in terrestrial ecosystems during the Jurassic. Some Jurassic sauropods reached gigantic sizes, becoming the largest organisms to have ever lived on land.
Basal bipedal sauropodomorphs
Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lon ...
, such as massospondylids, continued to exist into the Early Jurassic, but became extinct by the beginning of the Middle Jurassic. Quadrupedal sauropomorphs appeared during the Late Triassic. The quadrupedal ''Ledumahadi
''Ledumahadi'' (meaning "giant thunderclap" in Sesotho language) is a genus of lessemsaurid sauropodomorph dinosaur from the Early Jurassic Elliot Formation in Free State Province, South Africa. The type species, type and only species is ''L. maf ...
'' from the earliest Jurassic of South Africa reached an estimated weight of 12 tons, far in excess of other known basal sauropodomorphs. Gravisauria
Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.Allain, R. and Aquesbi, N. (2008). "Anatomy and phylogenetic relationships of ''Tazoudasaurus naimi'' (Dinosauria, Sauropoda) from the late Ea ...
n sauropods
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
first appeared during the Early Jurassic, with the oldest definitive record being ''Vulcanodon
''Vulcanodon'' (meaning "volcano tooth") is an extinct genus of sauropod dinosaur from the Early Jurassic of southern Africa. The only known species is ''V. karibaensis''. Discovered in 1969 in Zimbabwe, it was regarded as the earliest-known sau ...
'' from Zimbabwe, likely of Sinemurian age. Eusauropods first appeared during the late Early Jurassic (Toarcian) and diversified during the Middle Jurassic; these included cetiosaurids, turiasaurs, and mamenchisaurs. Neosauropods such as macronarians
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
and diplodocoids
Diplodocoidea is a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like ''Supersaurus'', ''Diplodocus'', ''Apatosaurus'', and ''Amphicoelias''. Most had very long necks and long, ...
first appeared during the Middle Jurassic, before becoming abundant and globally distributed during the Late Jurassic.
Amphibians
The diversity of temnospondyls
Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carbo ...
had progressively declined through the Late Triassic, with only brachyopoids surviving into the Jurassic and beyond. Members of the family Brachyopidae
Brachyopidae is an extinct family of temnospondyl labyrintodonts. They evolved in the early Mesozoic and were mostly aquatic. A fragmentary find from Lesotho, Africa is estimated to have been long, the largest amphibian ever known to have lived ...
are known from Jurassic deposits in Asia, while the chigutisaurid ''Siderops
''Siderops'' is an extinct genus of chigutisaurid temnospondyl from Early Jurassic of Australia, containing the species ''S. kehli''. It is solely known from the holotype specimen, which consists of a nearly complete skull with mandible and pos ...
'' is known from the Early Jurassic of Australia. Modern lissamphibia
The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs, toads, and their extinct relatives), the Caudata (salamanders, newts, and their extinct relatives), ...
ns began to diversify during the Jurassic. The Early Jurassic ''Prosalirus
''Prosalirus'' is the name given to a fossilised prehistoric frog found in the Kayenta Formation of Arizona in 1981 by Farish Jenkins.''Geographica''; "Jurassic Frog hops into the record book", National Geographic; August 1996, pg.5. The type, an ...
'' thought to represent the first frog relative with a morphology capable of hopping like living frogs. Morphologically recognisable stem-frogs like the South American '' Notobatrachus'' are known from the Middle Jurassic, with modern crown-group frogs like '' Enneabatrachus'' and ''Rhadinosteus
''Rhadinosteus parvus'' (meaning "long slender bone") is an extinct species of prehistoric frogs that lived during the Late Jurassic.Foster, J. (2007). "''Rhadinosteus parvus''." ''Jurassic West: The Dinosaurs of the Morrison Formation and Their ...
'' appearing by the Late Jurassic. While the earliest salamander-line amphibians are known from the Triassic, crown group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...
salamanders first appear during the Middle to Late Jurassic in Eurasia, alongside stem-group relatives. Many Jurassic stem-group salamanders, such as ''Marmorerpeton
''Marmorerpeton'' is an extinct genus of prehistoric stem group-salamanders that lived in Britain during the Bathonian stage of the Middle Jurassic.
They are among the oldest known salamanders. Two species were named when the genus was first ...
'' and ''Kokartus
''Kokartus'' is an extinct genus of prehistoric stem-group salamander (Caudata) from the Middle Jurassic Balabansai Formation of Kyrgyzstan.
The absence of clear lines of arrested growth and annuli in long bones suggests that the animals lived i ...
'', are thought to have been neotenic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...
. Early representatives of crown group salamanders include ''Chunerpeton
''Chunerpeton tianyiensis'' is an extinct species of salamander from the Late Jurassic Daohugou Beds in Ningcheng County, Nei Mongol (Inner Mongolia), China. It is the only species classified under the genus ''Chunerpeton''. It was a small anima ...
, Pangerpeton
''Pangerpeton'' is an extinct genus of salamanders. Its monotypic species is ''Pangerpeton sinensis''.
''Pangerpeton'' is a metamorphosed, primitive salamander from the Late Jurassic Daohugou fossil bed near Wubaiding Village of Lingyuan City, L ...
'' and '' Linglongtriton'' from the Middle to Late Jurassic Yanliao Biota
The Yanliao Biota is the name given to an assembly of fossils preserved in northeastern China from the Middle to Late Jurassic.Xu, X., Zhou, Z., Sullivan, C. and Wang, Y., 2017. The Yanliao Biota: a trove of exceptionally preserved Middle-Late Jur ...
of China. These belong to the Cryptobranchoidea
The Cryptobranchoidea are a suborder of salamanders found in Asia, European Russia, and the United States. They are known as primitive salamanders, in contrast to Salamandroidea, the advanced salamanders. It has two living subdivisions, Cryptobr ...
, which contains living Asiatic and giant salamander
The Cryptobranchidae are a family of fully aquatic salamanders commonly known as the giant salamanders. They include the largest living amphibians. The family is native to China, Japan, and the eastern United States. They constitute one of two li ...
s. ''Beiyanerpeton
''Beiyanerpeton'' is an extinct genus of salamandroid amphibians known from the Late Jurassic of western Liaoning Province, China. It contains a single species, ''B. jianpingensis''.
Discovery
''Beiyanerpeton'' is known from the holotype sp ...
'', and '' Qinglongtriton'' from the same biota are thought to be early members of Salamandroidea
The Salamandroidea are a suborder of salamanders, referred to as advanced salamanders. The members of the suborder are found worldwide except for Antarctica, sub-Saharan Africa, and Oceania. They differ from suborder Cryptobranchoidea as the ang ...
, the group which contains all other living salamanders. Salamanders dispersed into North America by the end of the Jurassic, as evidenced by ''Iridotriton
''Iridotriton'' is an extinct genus of prehistoric salamander known from a fossil found in stratigraphic zone 6 of the late Jurassic Morrison FormationFoster, J. (2007). "Appendix." ''Jurassic West: The Dinosaurs of the Morrison Formation and T ...
'', found in the Late Jurassic Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...
. The oldest undisputed stem-caecilian
Caecilians (; ) are a group of limbless, vermiform or serpentine amphibians. They mostly live hidden in the ground and in stream substrates, making them the least familiar order of amphibians. Caecilians are mostly distributed in the tropics of ...
is the Early Jurassic ''Eocaecilia
''Eocaecilia'' is an extinct genus of gymnophionan amphibian from the early Jurassic Kayenta Formation of Arizona, United States. One species is described, ''Eocaecilia micropodia''.
''Eocaecilia'' shared some characteristics with salamanders a ...
'' from Arizona. The fourth group of lissamphibians, the extinct albanerpetontids, first appeared in the Middle Jurassic, represented by '' Anoualerpeton priscus'' from the Bathonian of Britain, as well as indeterminate remains from equivalently aged sediments in France and the Anoual Formation
The Anoual Formation is a geological formation in the High Atlas of Morocco. It is early Bathonian
In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma ...
of Morocco.
Mammaliaformes
Mammaliaformes
Mammaliaformes ("mammalian forms") is a clade that contains the crown group mammals and their closest Extinction, extinct relatives; the group adaptive radiation, radiated from earlier probainognathian cynodonts. It is defined as the clade origin ...
, having originated from cynodont
The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety ...
s at the end of the Triassic, diversified extensively during the Jurassic. Important groups of Jurassic Mammaliaformes include Morganucodonta
Morganucodonta ("Glamorgan teeth") is an extinct order of basal Mammaliaformes, a group including crown-group mammals (Mammalia) and their close relatives. Their remains have been found in Southern Africa, Western Europe, North America, India an ...
, Docodonta
Docodonta is an Order (biology), order of extinct Mammaliaformes, mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early Mammaliaformes, mammaliaforms by their relativel ...
, Eutriconodonta
Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia, Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack ''et al.'' in 1973 as a replacement name for the ...
, Dryolestida
Dryolestida is an extinct order of mammals, primarily and possibly exclusively known from the Jurassic and Cretaceous. They are considered members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they d ...
, Haramiyida
Haramiyida ("thief" from Arabic الحرامية (al ḥarāmiyah), "thief, bandit") is a possibly polyphyletic order of mammaliaform cynodonts or mammals of controversial taxonomic affinites. Their teeth, which are by far the most common remains ...
and Multituberculata
Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, a ...
. While most Jurassic mammalaliaformes are solely known from isolated teeth and jaw fragments, exceptionally preserved remains have revealed a variety of lifestyles. The docodontan ''Castorocauda
''Castorocauda'' is an extinct, semi-aquatic, superficially otter-like genus of docodont mammaliaforms with one species, ''C. lutrasimilis''. It is part of the Yanliao Biota, found in the Daohugou Beds of Inner Mongolia, China dating to the M ...
'' was adapted to aquatic life, similarly to the platypus
The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal Endemic (ecology), endemic to Eastern states of Australia, eastern Australia, including Tasmania. The platypu ...
and otter
Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine, with diets based on fish and invertebrates. Lutrinae is a branch of the Mustelidae family, which also includes wea ...
s. Some members of Haramiyida and the eutriconodontan tribe Volaticotherini
Volaticotherini is a clade of eutriconodont mammals from the Mesozoic. In addition to the type genus ''Volaticotherium'', it includes the genera ''Argentoconodon'', ''Ichthyoconodon'', and potentially ''Triconolestes''.
Since most remains are p ...
[Meng, J.; Hu, Y.-M.; Wang, Y.-Q.; Wang, X.-L.; Li, C.-K. (2007). "Corrigendum: A Mesozoic gliding mammal from northeastern China". Nature 446 (7131): 102. . .] had a patagium
The patagium (plural: patagia) is a membranous body part that assists an animal in obtaining lift when gliding or flight. The structure is found in extant and extinct groups of flying and gliding animals including bats, birds, some dromaeosaurs ...
akin to those of flying squirrel
Flying squirrels (scientifically known as Pteromyini or Petauristini) are a tribe of 50 species of squirrels in the family Sciuridae. Despite their name, they are not in fact capable of full flight in the same way as birds or bats, but they ar ...
s, allowing them to glide through the air. The aardvark
The aardvark ( ; ''Orycteropus afer'') is a medium-sized, burrowing, nocturnal mammal native to Africa. It is the only living species of the order Tubulidentata, although other prehistoric species and genera of Tubulidentata are known. Unlike ...
-like mammal ''Fruitafossor
''Fruitafossor'' was a termite-eating mammal endemic to North America during the Late Jurassic epoch (around 150 mya).
The description is based on a complete skeleton of a chipmunk-sized animal.
It was discovered on March 31, 2005, in Fruita, ...
'', of uncertain taxonomy, was likely a specialist on colonial insects, similarly to living anteater
Anteater is a common name for the four extant mammal species of the suborder Vermilingua (meaning "worm tongue") commonly known for eating ants and termites. The individual species have other names in English and other languages. Together with ...
s. Australosphenida
The Australosphenida are a clade of mammals, containing mammals with tribosphenic molars, known from the Jurassic to Mid-Cretaceous of Gondwana. They are thought to have acquired their tribosphenic molars independently from those of Tribosphenida ...
, a group of mammals possibly related to monotremes, first appeared in the Middle Jurassic of Gondwana. Theria
Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes.
Ch ...
n mammals, represented today by living placentals
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguishe ...
and marsupial
Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a po ...
s, appear during the early Late Jurassic, represented by ''Juramaia
''Juramaia'' is an extinct genus of very basal eutherian mammal known from the Late Jurassic ( Oxfordian stage) deposits of western Liaoning, China. It is a small shrew-like mammal with a body length of approximately 70–100 mm, making it ...
,'' a eutheria
Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials.
Eutherians are distinguished from noneutherians by various phenotypic tra ...
n mammal closer to the ancestry of placentals than marsupials.[Electronic supplementary material]
/ref> ''Juramaia'' is much more advanced than expected for its age, as other therian mammals are not known until the Early Cretaceous. Two groups of non-mammalian cynodonts persisted beyond the end of the Triassic. The insectiviorous Tritheledontidae
Tritheledontidae, the tritheledontids or ictidosaurs, is an extinct family of small to medium-sized (about 10 to 20 cm long) cynodonts. They were highly mammal-like, specialized cynodonts, although they still retained a few reptile-like ana ...
has a few records from the Early Jurassic. The Tritylodontidae
Tritylodontidae ("three-knob teeth", named after the shape of their cheek teeth) is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, bearing several mammalian traits like erect limbs, endothermy and detail ...
, a herbiviorous group of cynodonts that first appeared during the Rhaetian, has abundant records from the Jurassic, overwhelmingly from the Northern Hemisphere.
Fish
Conodonts
The last known species of conodont
Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...
, a class of jawless fish
Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes ...
whose hard, tooth-like elements are key index fossils, finally became extinct during the earliest Jurassic after over 300 million years of evolutionary history, with an asynchronous extinction occurring first in the Tethys and eastern Panthalassa and survivors persisting into the earliest Hettangian of Hungary and central Panthalassa. End-Triassic conodonts were represented by only a handful of species and had been progressively declining through the Middle and Late Triassic.
Sarcopterygii
Lungfish
Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...
(Dipnoi) were present in freshwater environments of both hemispheres during the Jurassic. Genera include ''Ceratodus
''Ceratodus'' (from el, κέρας , 'horn' and el, ὀδούς 'tooth') was a wide-ranging genus of extinct lungfish. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found ...
'' and ''Ptychoceratodus
''Ptychoceratodus'' is an extinct genus of lungfish living from Early Triassic to Middle Jurassic. It was established by Otto Jaekel for one species (''P. runcinatus''), transferred from ''Ceratodus'' genus. Type species is ''P. serratus'' from ...
'', which are more closely related to living South American
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
and African lungfish
''Protopterus'' is the genus of four species of lungfish found in Africa. ''Protopterus'' was formerly thought to be the sole genus in the family Protopteridae, but more recent studies have classified it with ''Lepidosiren'' in the family Lepid ...
than Queensland lungfish
The Australian lungfish (''Neoceratodus forsteri''), also known as the Queensland lungfish, Burnett salmon and barramunda, is the only surviving member of the family Neoceratodontidae. It is one of only six extant lungfish species in the world. ...
, and '' Ferganoceratodus'' from the Jurassic of Asia, which is not closely related to either group of living lungfish. Mawsoniids, a marine and freshwater/brackish group of coelacanth
The coelacanths ( ) are fish belonging to the order Actinistia that includes two extant species in the genus ''Latimeria'': the West Indian Ocean coelacanth (''Latimeria chalumnae''), primarily found near the Comoro Islands off the east coast ...
s, which first appeared in North America during the Triassic, expanded into Europe and South America by the end of the Jurassic. The marine Latimeriidae
Latimeriidae is the only extant family of coelacanths, an ancient lineage of lobe-finned fish. It contains two extant species in the genus ''Latimeria'', found in deep waters off the coasts of southern Africa and east-central Indonesia. In additio ...
, which contains the living coelacanths of the genus ''Latimeria
''Latimeria'' is a rare genus of fish which contains the only living species of coelacanth. It includes two Extant taxon, extant species: the West Indian Ocean coelacanth (''Latimeria chalumnae'') and the Indonesian coelacanth (''Latimeria menado ...
'', were also present in the Jurassic, having originated in the Triassic.
Actinopterygii
Ray-finned fish (Actinopterygii
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
) were major components of Jurassic freshwater and marine ecosystems. Archaic "palaeoniscoid
Palaeoniscidae is an extinct family of ray-finned fishes (Actinopterygii) ascribed to the order Palaeonisciformes. The family includes the genus '' Palaeoniscum'' and potentially other Palaeozoic and Mesozoic early actinopterygian genera. The n ...
" fish, which were common in both marine and freshwater habitats during the preceding Triassic declined during the Jurassic, being largely replaced by more derived
Derive may refer to:
* Derive (computer algebra system), a commercial system made by Texas Instruments
* ''Dérive'' (magazine), an Austrian science magazine on urbanism
*Dérive, a psychogeographical concept
See also
*
*Derivation (disambiguatio ...
actinopterygian lineages. The oldest known Acipenseriformes
Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest div ...
, the group that contains living sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretace ...
and paddlefish
Paddlefish (family Polyodontidae) are a family of ray-finned fish belonging to order Acipenseriformes, and one of two living groups of the order alongside sturgeons (Acipenseridae). They are distinguished from other fish by their titular elongla ...
, are from the Early Jurassic. Amiiform fish (which today only includes the bowfin
The bowfin (''Amia calva'') is a bony fish, native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being the sole surviving species of the Halecomorphi ...
) first appeared during the Early Jurassic, represented by ''Caturus
''Caturus'' (from el, κατω , 'down' and el, οὐρά 'tail') is an extinct genus of fishes in the family Caturidae in the order Amiiformes, related to modern bowfin. Fossils of this genus range from 200 to 109 mya. It has been suggested ...
'' from the Pliensbachian of Britain; after their appearance in the western Tethys, they expanded to Africa, North America and Southeast and East Asia by the end of the Jurassic. Pycnodontiformes
Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America ...
, which first appeared in the western Tethys during the Late Triassic, expanded to South America and Southeast Asia by the end of the Jurassic, having a high diversity in Europe during the Late Jurassic. During the Jurassic, the Ginglymodi
Ginglymodi is a clade of ray-finned fish containing modern-day gars (Lepisosteidae) and their extinct relatives, including the family Lepidotidae and the orders Semionotiformes and Kyphosichthyiformes, and various other extinct taxa. Ginglymodi ...
, the only living representatives being gar
Gars are members of the family Lepisosteidae, which are the only surviving members of the Ginglymodi, an ancient holosteian group of ray-finned fish, which first appeared during the Triassic, over 240 million years ago. Gars comprise seven livin ...
s (Lepisosteidae) were diverse in both freshwater and marine environments. The oldest known representatives of anatomically modern gars appeared during the Upper Jurassic. Stem-group teleost
Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...
s, which make up over 99% of living Actinopterygii, had first appeared during the Triassic in the western Tethys; they underwent a major diversification beginning in the Late Jurassic, with early representatives of modern teleost clades such as Elopomorpha
The superorder Elopomorpha contains a variety of types of fishes that range from typical silvery-colored species, such as the tarpons and ladyfishes of the Elopiformes and the bonefishes of the Albuliformes, to the long and slender, smooth-bodi ...
and Osteoglossoidei
Osteoglossoidei are a suborder of the order Osteoglossiformes (Latin: "bony tongues") that contains the butterflyfish, the arowanas and bonytongue
Arapaiminae is a subfamily of freshwater osteoglossiform (bony-tongued) fishes belonging to the ...
appearing during this time. The Pachycormiformes
Pachycormiformes is an extinct order of marine ray-finned fish known from the Early Jurassic to the end of the Cretaceous. It only includes a single family, Pachycormidae. They were characterized by having serrated pectoral fins (though more rece ...
, a group of marine stem-teleosts, first appeared in the Early Jurassic and included both tuna
A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...
-like predatory and filter-feeding forms, the latter included the largest bony fish known to have existed: ''Leedsichthys
''Leedsichthys'' is an extinct genus of pachycormid fish that lived in the oceans of the Middle to Late Jurassic.Liston, JJ (2004). An overview of the pachycormiform ''Leedsichthys''. In: Arratia G and Tintori A (eds) Mesozoic Fishes 3 - System ...
'', with an estimated maximum length of over 15 metres, known from the late Middle to Late Jurassic.[Liston, J., Newbrey, M., Challands, T., and Adams, C., 2013, "Growth, age and size of the Jurassic pachycormid ''Leedsichthys problematicus'' (Osteichthyes: Actinopterygii) in: Arratia, G., Schultze, H. and Wilson, M. (eds.) ''Mesozoic Fishes 5 – Global Diversity and Evolution''. Verlag Dr. Friedrich Pfeil, München, Germany, pp. 145–175]
Chondrichthyes
During the Early Jurassic, the shark-like hybodonts
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like chondrichthyans, which existed from the late Devonian to the Late Cretaceous. They form the group of Elasmobranchii closest to neoselachians, the clade of modern shark ...
, which represented the dominant group of chondrichthyians during the preceding Triassic, were common in both marine and freshwater settings; however, by the Late Jurassic, hybodonts had become minor components of most marine communities, having been largely replaced by modern neoselachians, but remained common in freshwater and restricted marine environments. The Neoselachii, which contains all living sharks and rays, radiated beginning in the Early Jurassic. The oldest known ray (Batoidea
Batoidea is a superorder of cartilaginous fishes, commonly known as rays. They and their close relatives, the sharks, comprise the subclass Elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 fa ...
) is ''Antiquaobatis
''Antiquaobatis'' is an extinct genus of ray from the Early Jurassic (Late Pliensbachian) of Europe, containing the single species ''A. grimmenensis''. It is the oldest known described member of the Rajiformes, and is based on a single tooth fro ...
'' from the Pliensbachian of Germany. Jurassic batoids known from complete remains retain a conservative, guitarfish
The guitarfish, also referred to as shovelnose rays, are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small, ray-like wings. The combined range of the various species is trop ...
-like morphology. The oldest known Hexanchiformes
The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just seven extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.
Hexanchi ...
and carpet shark
Carpet sharks are sharks classified in the order Orectolobiformes . Sometimes the common name "carpet shark" (named so because many species resemble ornately patterned carpets) is used interchangeably with "wobbegong", which is the common name o ...
s (Orectolobiformes) are from the Early Jurassic (Pliensbachian & Toarcian, respectively) of Europe. The oldest known members of the Heterodontiformes, the only living member of which is the bullhead shark (''Heterodontus''), first appeared in the Early Jurassic, with representatives of the living genus appearing during the Late Jurassic. The oldest known mackerel sharks
The Lamniformes (, from Greek ''lamna'' "fish of prey") are an order of sharks commonly known as mackerel sharks (which may also refer specifically to the family Lamnidae). It includes some of the most familiar species of sharks, such as the gr ...
(Lamniformes) are from the Middle Jurassic, represented by the genus ''Palaeocarcharias
''Palaeocarcharias'' is an extinct genus of shark, known from the Middle-Late Jurassic of Europe. It has only a single named species, ''P. stromeri,'' which is known from exceptionally preserved specimens from the Late Jurassic (Tithonian) of Germ ...
'', which has an orectolobiform-like body but shares key similarities in tooth histology
Histology,
also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...
with lamniformes, including the absence of orthodentine. The oldest record of angelshark
The angelsharks are a group of sharks in the genus ''Squatina'' of the family Squatinidae. They commonly inhabit sandy seabeds close to in depth. Many species are now classified as critically endangered by the International Union for Conservat ...
s (Squatiniformes) is ''Pseudorhina
''Pseudorhina'' is an extinct genus of stem angel shark seemingly restricted to the Mesozoic of Europe. It is represented by several articulated individuals as well as isolated teeth. There are four species.
Taxonomy and relationships
''Pseud ...
'' from the Late Jurassic (Oxfordian–Tithonian) of Europe, which already has a bodyform similar to living members of the order. The oldest known remains of Carcharhiniformes
Carcharhiniformes , the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark.
Members of this order are characterized by the presen ...
, the largest order of living sharks, first appear in the late Middle Jurassic (Bathonian) of the western Tethys (England and Morocco). Known dental and exceptionally preserved body remains of Jurassic Carchariniformes are similar to those of living catshark
Catsharks are ground sharks of the family Scyliorhinidae. They are the largest family of sharks with around 160 species placed in 17 genera. Although they are generally known as catsharks, some species can also be called dogfish due to previous n ...
s. Synechodontiformes
Synechodontiformes is an extinct order of prehistoric sharks, known from the Permian to the Paleogene. They are considered to be members of Neoselachii, the group that contains modern sharks and rays. Their placement in the group is uncertain, s ...
, an extinct group of sharks closely related to Neoselachii, were also widespread during the Jurassic. The oldest remains of modern chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
At ...
s are from the Early Jurassic of Europe, with members of the living family Callorhinchidae
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
At ...
appearing during the Middle Jurassic. Unlike living chimaeras, these were found in shallow water settings. The closely related ''Squaloraja
''Squaloraja polyspondyla'' is an extinct chimaeriform fish from the Lower Jurassic of Europe. Fossils of ''S. polyspondyla'' have been found in Lower Jurassic-aged marine strata of Lyme Regis, England, and Osteno, Italy.
Individuals of ''S. p ...
'' and myriacanthoids are also known from the Jurassic of Europe.
Insects and arachnids
There appears to have been no major extinction of insects at the Triassic–Jurassic boundary. Many important insect fossil localities are known from the Jurassic of Eurasia, the most important being the Karabastau Formation
The Karabastau Formation ( kk, Qarabastaý svıtasy) is a geological formation and lagerstätte in the Karatau Mountains of southern Kazakhstan whose strata date to the Middle to Late Jurassic. It is an important locality for insect fossils that ...
of Kazakhstan and the various Yanliao Biota deposits in Inner Mongolia, China, such as the Daohugou Bed, dating to the Callovian–Oxfordian. The diversity of insects stagnated throughout the Early and Middle Jurassic, but during the latter third of the Jurassic origination rates increased substantially while extinction rates remained flat. The increasing diversity of insects in the Middle–Late Jurassic corresponds with a substantial increase in the diversity of insect mouthparts
Insects have mouthparts that may vary greatly across insect species, as they are adapted to particular modes of feeding. The earliest insects had chewing mouthparts. Most specialisation of mouthparts are for piercing and sucking, and this mode o ...
. The Middle to Late Jurassic was a time of major diversification for beetle
Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
s. Weevil
Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...
s first appear in the fossil record during the Middle to Late Jurassic, but are suspected to have originated during the Late Triassic to Early Jurassic. The oldest known lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
ns (the group containing butterflies and moths) are known from the Triassic–Jurassic boundary, with wing scales belonging to the suborder Glossata
Glossata (Fabricius, 1775) is the suborder of the insect order Lepidoptera that contains most lepidopteran species and includes all the Superfamily (zoology), superfamilies of moths and butterfly, butterflies that have a coilable proboscis. (See ...
and Micropterigidae
Micropterigoidea is the superfamily of "mandibulate archaic moths", all placed in the single family Micropterigidae, containing currently about twenty living genera. They are considered the most primitive extant lineage of lepidoptera (Kristense ...
-grade moths from the deposits of this age in Germany. Modern representatives of both dragonflies
A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonfly are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threa ...
and damselflies
Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, Anisoptera, but are smaller and have slimmer bodies. Most species fold the wings along ...
also first appeared during the Jurassic. Although modern representatives are not known until the Cenozoic, ectoparasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
insects thought to represent primitive flea
Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, a ...
s, belonging to the family Pseudopulicidae
Pseudopulicidae is an extinct family of stem-group fleas from the Middle Jurassic to Early Cretaceous of China. They represent the oldest known group of stem-fleas. Like other stem-group "giant fleas", they are much larger and lack the specialised ...
, are known from the Middle Jurassic of Asia. These insects are substantially different from modern fleas, lacking the specialised morphology of the latter and being larger. Parasitoid wasps
Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causi ...
(Apocrita
Apocrita is a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" ( petiole) formed ...
) first appeared during the Early Jurassic and subsequently became widespread, reshaping terrestrial food webs. The Jurassic saw also saw the first appearances of several other groups of insects, including Phasmatodea
The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as ...
(stick insects), Mantophasmatidae
Mantophasmatidae is a family (biology), family of carnivorous wingless insects within the order Notoptera, which was discovered in Africa in 2001.K.-D. Klass, O. Zompro, N.P. Kristensen, J. Adis. Mantophasmatodea: a new insect order with extant ...
, Embioptera
The order (biology), order Embioptera, commonly known as webspinners or footspinners, are a small group of mostly Tropics, tropical and Subtropics, subtropical insects, classified under the Subclass (biology), subclass Pterygota. The order has ...
(webspinners), and Raphidioptera
Snakeflies are a group of predatory insects comprising the order Raphidioptera with two extant families: Raphidiidae and Inocelliidae, consisting of roughly 260 species. In the past, the group had a much wider distribution than it does now; sn ...
(snakeflies).
Only a handful of records of mites are known from the Jurassic, including '' Jureremus'', an oribatid mite belonging to the family Cymbaeremaeidae known from the Late Jurassic of Britain and Russia, and a member of the still living orbatid genus '' Hydrozetes'' from the Early Jurassic of Sweden. Spiders diversified through the Jurassic. The Early Jurassic '' Seppo koponeni'' may represent a stem group to Palpimanoidea
The Palpimanoidea or palpimanoids, also known as assassin spiders, are a group of araneomorph spiders, originally treated as a superfamily. As with many such groups, its circumscription has varied. , the following five families were included:
* ...
. '' Eoplectreurys'' from the Middle Jurassic of China is considered a stem lineage of Synspermiata
Synspermiata is a clade of araneomorph spiders, comprising most of the former " haplogynes". They are united by having simpler genitalia than other araneomorph spiders, lacking a cribellum, and sharing an evolutionary history of synspermia – a ...
. The oldest member of the family Archaeidae
Archaeidae, also known as assassin spiders and pelican spiders, is a spider family with about ninety described species in five genera. It contains small spiders, ranging from long, that prey exclusively on other spiders. They are unusual in that ...
, '' Patarchaea'', is known from the Middle Jurassic of China. ''Mongolarachne
''Mongolarachne'' is an extinct genus of spiders placed in the monogeneric family Mongolarachnidae. The genus contains only one species, ''Mongolarachne jurassica'', described in 2013, which is presently the largest fossilized spider on record. ...
'' from the Middle Jurassic of China is among the largest known fossil spiders, with legs over 5 centimetres long. The only scorpion known from the Jurassic is ''Liassoscorpionides
''Liassoscorpionides'' is an extinct genus of scorpions from the Toarcian of Germany. It was found on the Posidonia Shale, on the so-called insect beds of Hondelage near Braunschweig, on a layer, as its name suggests, full of insect genera. ''Lia ...
'' from the Early Jurassic of Germany, of uncertain placement. Eupnoi
The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species.
They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group C ...
harvestmen (Opiliones
The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of ext ...
) are known from the Middle Jurassic of China, including members of the family Sclerosomatidae
The Sclerosomatidae are a family of harvestmen with about 1,300 known species.
Name
The name is combined from Ancient Greek ''skleros'' "hard" and ''soma'' "body". (2007): Sclerosomatidae. Simon, 1879. In: Pinto-da-Rocha ''et al.'' 2007: 127ff
...
.
Marine invertebrates
End-Triassic extinction
During the end-Triassic extinction, 46%–72% of all marine genera became extinct. The effects of the end Triassic extinction were greatest at tropical latitudes and were more severe in Panthalassa than the Tethys or Boreal oceans. Tropical reef ecosystems collapsed during the event, and would not fully recover until much later in the Jurassic. Sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
filter feeder
Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
s and photosymbiotic organisms were among most severely affected.
Marine ecosystems
Having declined at the Triassic–Jurassic boundary, reefs substantially expanded during the Late Jurassic, including both sponge reef
Sponge reefs are reefs formed by Hexactinellid sponges, which have a skeleton made of silica, and are often referred to as ''glass sponges''. Such reefs are now very rare, and found only in waters off the coast of British Columbia, Washington ( ...
s and scleractinia
Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyp (zoology), polyps and have a cylindrical body crowned by an oral di ...
n coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Co ...
s. Late Jurassic reefs were similar in form to modern reefs but had more microbial carbonates and hypercalcified sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...
s, and had weak biogenic binding. Reefs sharply declined at the close of the Jurassic, which caused an associated drop in diversity in decapod crustaceans. The earliest planktonic foraminifera, which constitute the suborder Globigerinina
The Globigerinina is a suborder of foraminiferans that are found as marine plankton. They produce hyaline calcareous tests, and are known as fossils from the Jurassic period onwards. The group has included more than 100 genera and over 400 spec ...
, are known from the late Early Jurassic (mid-Toarcian) of the western Tethys, expanding across the whole Tethys by the Middle Jurassic and becoming globally distributed in tropical latitudes by the Late Jurassic. Coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdo ...
s and dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
s, which had first appeared during the Triassic, radiated during the Early to Middle Jurassic, becoming prominent members of the phytoplankton
Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'.
Ph ...
. Microconchid tube worms, the last remaining order of Tentaculita
Tentaculita is an extinct class of uncertain placement ranging from the Early Ordovician to the Middle Jurassic. They were suspension feeders with a near worldwide distribution. For a more thorough discussion, see ''Tentaculites''.
The presenc ...
, a group of animals of uncertain affinities that were convergent on ''Spirorbis
''Spirorbis'' is a genus of very small () polychaete worms, usually with a white coiled shell. Members of the genus live in the lower littoral and sublittoral zones of rocky shores. ''Spirorbis'' worms usually live attached to seaweeds, but some ...
'' tube worms, were rare after the Triassic and had become reduced to the single genus ''Punctaconchus
''Punctaconchus'' is a genus of microconchid tubeworms. It was the last genus of microconchids, and the only genus to exist beyond the Triassic. Their tubes have large pores (punctae) penetrating the tube wall. Tubes lumen is covered by
ripplemar ...
,'' which became extinct in the late Bathonian. The oldest known diatom
A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
is from Late Jurassic–aged amber from Thailand, assigned to the living genus '' Hemiaulus.''
Echinoderms
Crinoid
Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...
s diversified throughout the Jurassic, reaching their peak Mesozoic diversity during the Late Jurassic, primarily due to the radiation of sessile forms belonging to the orders Cyrtocrinida
Cyrtocrinida is an order of sea lilies which contains two suborders and three families.
Characteristics
Members of this order have stems consisting of a single skeletal unit or a very small number of units. There are no cirri, and the expanded ...
and Millericrinida
Millericrinida is an order of articulate crinoids that originated in the Anisian
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until millio ...
. Echinoids
Sea urchins () are spine (zoology), spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard s ...
(sea urchins) underwent substantial diversification beginning in the Early Jurassic, primarily driven by the radiation of irregular (asymmetrical) forms, which were adapting to deposit feeding. Rates of diversification sharply dropped during the Late Jurassic.
Crustaceans
The Jurassic was a significant time for the evolution of decapods
The Decapoda or decapods (literally "ten-footed") are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, shrimp and prawns. Most decapods are scavengers. The order is estim ...
. The first true crabs ( Brachyura) are known from the Early Jurassic, with the earliest being '' Eocarcinus praecursor'' from the early Pliensbachian of England, which lacked the crab-like morphology (carcinisation
Carcinisation (or carcinization) is an example of convergent evolution in which a crustacean evolves into a crab-like form from a non-crab-like form. The term was introduced into evolutionary biology by L. A. Borradaile, who describe ...
) of modern crabs, and ''Eoprosopon klugi'' from the late Pliensbachian of Germany, which may belong to the living family Homolodromiidae
Homolodromiidae is a family of crabs, the only family in the superfamily Homolodromioidea. In contrast to other crabs, including the closely related Homolidae, there is no strong ''linea homolica'' along which the exoskeleton
An exoskeleton ...
. Most Jurassic crabs are known only from carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
pieces, which makes it difficult to determine their relationships. While rare in the Early and Middle Jurassic, crabs became abundant during the Late Jurassic as they expanded from their ancestral silty sea floor habitat into hard substrate habitats like reefs, with crevices in reefs providing refuge from predators. Hermit crab
Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an a ...
s also first appeared during the Jurassic, with the earliest known being '' Schobertella hoelderi'' from the late Hettangian of Germany. Early hermit crabs are associated with ammonite shells rather than those of gastropods. Glypheids, which today are only known from two species, reached their peak diversity during the Jurassic, with around 150 species out of a total fossil record of 250 known from the period. Jurassic barnacles were of low diversity compared to present, but several important evolutionary innovations are known, including the first appearances of calcite shelled forms and species with an epiplanktonic mode of life.
Brachiopods
Brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...
diversity declined during the Triassic–Jurassic extinction. Spire-bearing groups (Spiriferinida and Athyridida) declined at the Triassic–Jurassic boundary and did not recover their biodiversity, becoming extinct in the TOAE. Rhynchonellida and Terebratulida also declined during the Triassic–Jurassic extinction but rebounded during the Early Jurassic; neither clade underwent much morphological variation. Brachiopods substantially declined in the Late Jurassic; the causes are poorly understood. Proposed reasons include increased predation, competition with bivalves, enhanced bioturbation or increased grazing pressure.
Bryozoans
Like the preceding Triassic, bryozoan diversity was relatively low compared to the Paleozoic. The vast majority of Jurassic bryozoans are members of Cyclostomatida, which experienced a radiation during the Middle Jurassic, with all Jurassic representatives belonging to the suborders Tubuliporina and List of Cyclostomatida families, Cerioporina. Cheilostomata, the dominant group of modern bryozoans, first appeared during the Late Jurassic.
Molluscs
= Bivalves
=
The end-Triassic extinction had a severe impact on bivalve diversity, though it had little impact on bivalve ecological diversity. The extinction was selective, having less of an impact on deep burrowers, but there is no evidence of a differential impact between surface-living (epifaunal) and burrowing (infaunal) bivalves. Bivalve family level diversity after the Early Jurassic was static, though genus diversity experienced a gradual increase throughout the period. Rudists, the dominant reef-building organisms of the Cretaceous, first appeared in the Late Jurassic (mid-Oxfordian) in the northern margin of the western Tethys, expanding to the eastern Tethys by the end of the Jurassic.
= Cephalopods
=
Ammonites were devastated by the end-Triassic extinction, with only a handful of genera belonging to the family Psiloceratidae of the suborder Phylloceratina surviving and becoming ancestral to all later Jurassic and Cretaceous ammonites. Ammonites explosively diversified during the Early Jurassic, with the orders Psiloceratina, Ammonitina, Lytoceratina, Haploceratoidea, Haploceratina, Perisphinctoidea, Perisphinctina and Ancyloceratina all appearing during the Jurassic. Ammonite faunas during the Jurassic were regional, being divided into around 20 distinguishable provinces and subprovinces in two realms, the northern high latitude Pan-Boreal realm, consisting of the Arctic, northern Panthalassa and northern Atlantic regions, and the equatorial–southern Pan-Tethyan realm, which included the Tethys and most of Panthalassa.
The oldest definitive records of the squid-like Belemnitida, belemnites are from the earliest Jurassic (Hettangian–Sinemurian) of Europe and Japan; they expanded worldwide during the Jurassic. Belemnites were shallow-water dwellers, inhabiting the upper 200 metres of the water column on the Continental shelf, continental shelves and in the littoral zone. They were key components of Jurassic ecosystems, both as predators and prey, as evidenced by the abundance of belemnite guards in Jurassic rocks.
The earliest Vampyromorphida, vampyromorphs, of which the only living member is the vampire squid, first appeared during the Early Jurassic. The earliest octopuses appeared during the Middle Jurassic, having split from their closest living relatives, the vampyromorphs, during the Triassic to Early Jurassic. All Jurassic octopuses are solely known from the hard Gladius (cephalopod), gladius. Octopuses likely originated from bottom-dwelling (Benthic zone, benthic) ancestors which lived in shallow environments. ''Proteroctopus'' from the late Middle Jurassic La Voulte-sur-Rhône (lagerstätte), La Voulte-sur-Rhône lagerstätte, previously interpreted as an early octopus, is now thought to be a basal taxon outside the clade containing vampyromorphs and octopuses.
References
Citations
External links
Examples of Jurassic Fossils
Jurassic fossils in Harbury, Warwickshire
Jurassic Microfossils: 65+ images of Foraminifera
* With map and table.
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Jurassic,
Geological periods