Etymology and history
TheGeology
The Jurassic Period is divided into threeStratigraphy
Jurassic stratigraphy is primarily based on the use of ammonites asEarly 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 precedingMiddle Jurassic
The Aalenian is named after the city ofUpper Jurassic
The Oxfordian is named after the city of Oxford in England and was named by Alcide d'Orbigny in 1844 in reference to the Oxford Clay. The base of the Oxfordian lacks a defined GSSP. William Joscelyn Arkell, W. J. Arkell in studies in 1939 and 1946 placed the lower boundary of the Oxfordian as the first appearance of the ammonite ''Quenstedtoceras, Quenstedtoceras mariae'' (then placed in the genus ''Vertumniceras''). Subsequent proposals have suggested the first appearance of ''Cardioceras, Cardioceras redcliffense'' as the lower boundary. The village of Kimmeridge on the coast of Dorset, 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 GSSP for the base of the Kimmeridgian is the Flodigarry section at Staffin, Staffin Bay on the Isle of Skye, Scotland, 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 rather than a place name. Tithonus was the son of Laomedon of Troy and fell in love with Eos, the Greek goddess of dawn. His name was chosen by Albert Oppel for this Stratigraphy, 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 (ammonite), 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 Chemostratigraphy, chemostratigraphic events, such as isotope excursions (large sudden changes in Stable isotope ratio, ratios of isotopes), that could be used to define or correlate a boundary. Calpionellids, an enigmatic group of planktonic protists with urn-shaped calcitic Test (biology), tests 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, Calpionella alpina,'' 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, 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 for the North Sea oil. 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, the world's largest oil field. The Jurassic-aged Sargelu and Naokelekan formations are major source rocks for Oil reserves in Iraq, oil in Iraq. Over 1500 gigatons of Jurassic coal reserves are found in north-west China, primarily in the Turpan Depression, Turpan-Hami Basin and the Ordos Plateau, Ordos Basin.Impact structures
Major impact structures include the Morokweng impact structure, 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, 40 kilometres in diameter, buried beneath Nizhny Novgorod Oblast in western Russia. The impact has been dated to the Sinemurian, 195.9 ± 1.0 Ma.Paleogeography and tectonics
At the beginning of the Jurassic, all of the world's major landmasses were coalesced into theClimate
The climate of the Jurassic was generally warmer than that of present, by around 5 °C to 10 °C, with Carbon dioxide in Earth's atmosphere, atmospheric carbon dioxide 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. Dropstones and glendonites in northeastern Siberia during the Early to Middle Jurassic indicate cold winters.Alt URLClimatic 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 ratio, carbon isotope excursion, as well as the deposition of black shale, shales 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 clathrates. This likely accelerated the hydrological cycle and increased Carbonate–silicate cycle, silicate weathering, as evidenced by an increased amount of organic matter of terrestrial origin found in marine deposits during the TOAE. Groups affected include ammonites, ostracods, foraminifera, Bivalvia, bivalves, cnidarians, and especially Brachiopoda, brachiopods, 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 was transformed into a giant lake, probably three times the size of modern-day Lake Superior, represented by the Da’anzhai Member of the Ziliujing Formation. The lake likely Carbon sequestration, 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. ThisEnd-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. At the end of the Triassic, the Peltaspermaceae became extinct in most parts of the world, with ''Lepidopteris'' persisting into the Early Jurassic in Patagonia. ''Dicroidium'', 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
Conifers 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 Voltziales, voltzialean ancestors. Araucariaceae, Araucarian conifers have their first unambiguous records during the Early Jurassic, and members of the modern genus ''Araucaria'' were widespread across both hemispheres by the Middle Jurassic. Also abundant during the Jurassic is the extinct family Cheirolepidiaceae, 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) is ''Austrohamia, 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'' and ''Cunninghamia.'' 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 to the pine family (Pinaceae), were widely distributed across Eurasia during the Jurassic. The oldest unambiguous record of Pinaceae is the Conifer cone, pine cone ''Eathiestrobus'', 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 Pinoideae, pinoid clade 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,'' 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) is ''Palaeotaxus, Palaeotaxus rediviva'', from the Hettangian of Sweden, suggested to be closely related to the living ''Austrotaxus'', while ''Marskea, Marskea jurassica'' from the Middle Jurassic of Yorkshire, England and material from the Callovian–Oxfordian Daohugou Bed in China are thought to be closely related to ''Amentotaxus,'' with the latter material assigned to the modern genus, indicating that Taxaceae had substantially diversified by the end of the Jurassic. Podocarpaceae, 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, of which the sole living species is ''Ginkgo biloba'', 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,'' represented by Ovule, ovulate 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'', ''Grenana'', ''Nagrenia'' and Karkeniaceae, ''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 (plant), 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, 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 stomata, and the two groups are not thought to be closely related. Jurassic Bennettitales predominantly belong to the group Williamsoniaceae, which grew as shrubs and small trees. The Williamsoniaceae are thought to have had a divaricate branching habit, similar to that of living ''Banksia'', and adapted to growing in open habitats with poor soil nutrient conditions. Bennettitales exhibit complex, flower-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 Kalligrammatidae, kalligrammatid lacewings and extant ones such as Acroceridae, acrocerid flies, are suggested to have been pollinators of bennettitales, feeding on nectar produced by bennettitalean cones.Cycads
Cycads 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, 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 plants, which make up 90% of living plant species, and fossil evidence suggests that the group diversified during the following Cretaceous. The earliest known Gnetophytes appeared by the end of the Jurassic. "Seed ferns" (Pteridospermatophyta) is a collective term to refer to disparate lineages of fern like plants that produce seeds but have uncertain affinities to living Spermatophyte, seed plant groups. A prominent group of Jurassic seed ferns is the Caytoniales, 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-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'' 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, a small but clearly distinct group of liana-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, Matoniaceae, Gleicheniaceae, Osmundaceae and Marattiaceae. Polypodiales, 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 plant, herbaceous fern genus ''Coniopteris,'' historically interpreted as a close relative of tree ferns of the family Dicksoniaceae, has recently been reinterpreted as an early relative of the group. The Cyatheales, 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 on the basis of cladistic analysis. Only a handful of possible records exist of the Hymenophyllaceae from the Jurassic, including ''Hymenophyllites macrosporangiatus'' from the Russian Jurassic. The oldest remains of modern Equisetaceae, horsetails of the genus ''Equisetum'' first appear in the Early Jurassic, represented by ''Equisetum dimorphum'' from the Early Jurassic of Patagonia and ''Equisetum laterale'' from the Early to Middle Jurassic of Australia. Petrifaction, Silicified remains of ''Equisetum thermale'' from the Late Jurassic of Argentina exhibit all the morphological characters of modern members of the genus. The estimated split between ''Equisetum bogotense'' and all other living ''Equisetum'' is estimated to have occurred no later than the Early Jurassic.Lower plants
Isoetes, 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, which grow on animal caracasses. ''Bryokhutuliinia'' from the same region is thought to be related to Dicranales. ''Heinrichsiella'' from the Jurassic of Patagonia is thought to belong to either Polytrichaceae or Timmiellaceae. The liverwort ''Pellites, Pellites hamiensis'' from the Middle Jurassic Xishanyao Formation of China is the oldest record of the family Pelliaceae. Pallaviciniites, ''Pallaviciniites sandaolingensis'' from the same deposit is thought to belong to the subclass Pallaviciniineae within the Pallaviciniales. ''Ricciopsis, Ricciopsis sandaolingensis'', also from the same deposit, is the only Jurassic record of Ricciaceae.Fauna
Reptiles
Crocodylomorphs
The Triassic–Jurassic extinction decimatedTurtles
Stem-group turtles (Testudinata) diversified during the Jurassic. Jurassic stem-turtles belong to two progressively more advanced clades, the Mesochelydia and Perichelydia. It is thought that the ancestral condition for mesochelydians is aquatic, as opposed to terrestrial for testudinates. The two modern groups of turtles (Turtle, Testudines), Pleurodira and Cryptodira, diverged by the beginning of the Late Jurassic. The oldest known pleurodires, the Platychelyidae, are known from the Late Jurassic of Europe and the Americas, while the oldest unambiguous cryptodire, ''Sinaspideretes,'' an early relative of Trionychidae, softshell turtles, is known from the Late Jurassic of China. The Thalassochelydia, a diverse lineage of marine turtles unrelated to modern Sea turtle, sea turtles, are known from the Late Jurassic of Europe and South America.Lepidosaurs
Rhynchocephalians (the sole living representative being the tuatara) 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 Pleurosauridae, pleurosaurs with long snake-like bodies and reduced limbs, the specialized herbivorous Eilenodontinae, eilenodontines, as well as ''Oenosaurus,'' which had broad tooth plates indicative of durophagy. Rhynchocephalians disappeared from Asia after the Early Jurassic. The last common ancestor of living Squamata, squamates (which includes lizards and snakes) 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, though many Jurassic squamates have unclear relationships to living groups. ''Eichstaettisaurus'' from the Late Jurassic of Germany has been suggested to be an early relative of geckos and displays adaptations for climbing. ''Dorsetisaurus'' from the Late Jurassic of North America and Europe represents the oldest widely accepted record of Anguimorpha. ''Tamaulipasaurus'' from Early Jurassic of Mexico and ''Marmoretta'' from the Middle Jurassic of Britain represents late surviving Lepidosauromorpha, lepidosauromorphs outside both Rhynchocephalia and Squamata.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'', 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'' from the Late Jurassic of China, which is a more advanced choristodere, though still small and lizard-like in morphology.Ichthyosaurs
Ichthyosaurs suffered an evolutionary bottleneck during the end-Triassic extinction, with all non-neoichthyosaurians becoming extinct. Ichthyosaurs reached their apex of species diversity during the Early Jurassic, with an array of morphologies including the huge apex predator ''Temnodontosaurus'' and swordfish-like ''Eurhinosaurus,'' 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, 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
Plesiosauria, Plesiosaurs originated at the end of the Triassic (Rhaetian). By the end of the Triassic, all other sauropterygians, including Placodontia, placodonts and nothosaurs, 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. 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 Microcleididae, 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 during the Bajocian. The Middle Jurassic saw the evolution of short-necked and large-headed Thalassophonea, thalassophonean pliosaurs from ancestrally small-headed, long-necked forms''.'' Some thalassophonean pliosaurs, such as some species of ''Pliosaurus'', 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
Pterosaurs first appeared in the Late Triassic. A major radiation of Jurassic pterosaurs is the Rhamphorhynchidae, which first appeared in the late Early Jurassic (Toarcian); they are thought to been Piscivore, piscivorous. Anurognathidae, Anurognathids, which first appeared in the Middle Jurassic, possessed short heads and densely furred bodies, and are thought to have been insectivores. Derived monofenestratan pterosaurs such as Wukongopteridae, wukongopterids appeared in the late Middle Jurassic. Advanced short-tailed Pterodactyloidea, pterodactyloids first appeared at the Middle–Late Jurassic boundary. Jurassic pterodactyloids include the Ctenochasmatoidea, ctenochasmatids, like ''Ctenochasma'', which have closely spaced needle-like teeth that were presumably used for Filter feeder, filter feeding. The bizarre Late Jurassic Ctenochasmatoidea, ctenochasmatoid ''Cycnorhamphus'' had a jaw with teeth only at the tips, with bent jaws like those of living openbill storks that may have been used to hold and crush hard invertebrates.Dinosaurs
Dinosaurs, 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'', 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 Theropoda, theropods belonging to Neotheropoda first appeared in the Late Triassic. Basal neotheropods, such as Coelophysoidea, coelophysoids and Dilophosauridae, dilophosaurs, persisted into the Early Jurassic, but became extinct by the Middle Jurassic. The earliest averostrans appear during the Early Jurassic, with the earliest known member of Ceratosauria being ''Saltriovenator'' from the early Sinemurian (199.3–197.5 million years ago) of Italy. The unusual ceratosaur ''Limusaurus'' from the Late Jurassic of China had a herbivorous diet, with adults having edentulous beaked jaws, making it the earliest known theropod to have converted from an ancestrally carnivorous diet. The earliest members of the Tetanurae appeared during the late Early Jurassic or early Middle Jurassic. The Megalosauridae represent the oldest radiation of the Tetanurae, first appearing in Europe during the Bajocian. The oldest member of Allosauroidea has been suggested to be ''Asfaltovenator'' from the Middle Jurassic of South America. Coelurosauria, Coelurosaurs first appeared during the Middle Jurassic, including early Tyrannosauroidea, tyrannosaurs such as ''Proceratosaurus'' from the Bathonian of Britain. Some coelurosaurs from the Late Jurassic of China including ''Shishugounykus'' and ''Haplocheirus'' are suggested to represent early Alvarezsauroidea, alvarezsaurs, however, this has been questioned. Scansoriopterygidae, 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 Troodontidae, troodontids is suggested to be ''Hesperornithoides'' from the Late Jurassic of North America. Tooth remains suggested to represent those of Dromaeosauridae, dromaeosaurs are known from the Jurassic, but no body remains are known until the Cretaceous.= Birds
= The earliest Avialae, avialans, which include birds and their ancestors, appear during the Middle to Late Jurassic, definitively represented by ''Archaeopteryx'' from the Late Jurassic of Germany. Avialans belong to the clade Paraves within Coelurosauria, which also includes dromaeosaurs and troodontids. The Anchiornithidae 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 ornithischians appear during the Early Jurassic, represented by basal ornithischians like ''Lesothosaurus'', Heterodontosauridae, heterodontosaurids, and early members of Thyreophora. The earliest members of Ankylosauria and Stegosauria appear during the Middle Jurassic. The basal neornithischian ''Kulindadromeus'' from the Middle Jurassic of Russia indicates that at least some ornithischians were covered in Feathered dinosaur, protofeathers. The earliest members of Ankylopollexia, which become prominent in the Cretaceous, appeared during the Late Jurassic, represented by bipedal forms such as ''Camptosaurus''. Ceratopsians first appeared in the Late Jurassic of China, represented by members of Chaoyangsauridae.Sauropodomorphs
Sauropoda, Sauropods 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 (phylogenetics), Basal bipedal Sauropodomorpha, sauropodomorphs, such as Massospondylidae, 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'' from the earliest Jurassic of South Africa reached an estimated weight of 12 tons, far in excess of other known basal sauropodomorphs. Gravisaurian Sauropoda, sauropods first appeared during the Early Jurassic, with the oldest definitive record being ''Vulcanodon'' from Zimbabwe, likely of Sinemurian age. Eusauropoda, Eusauropods first appeared during the late Early Jurassic (Toarcian) and diversified during the Middle Jurassic; these included Cetiosauridae, cetiosaurids, Turiasauria, turiasaurs, and Mamenchisauridae, mamenchisaurs. Neosauropoda, Neosauropods such as Macronaria, macronarians and Diplodocoidea, diplodocoids first appeared during the Middle Jurassic, before becoming abundant and globally distributed during the Late Jurassic.Amphibians
The diversity of Temnospondyli, temnospondyls had progressively declined through the Late Triassic, with only Brachyopoidea, brachyopoids surviving into the Jurassic and beyond. Members of the family Brachyopidae are known from Jurassic deposits in Asia, while the Chigutisauridae, chigutisaurid ''Siderops'' is known from the Early Jurassic of Australia. Modern lissamphibians began to diversify during the Jurassic. The Early Jurassic ''Prosalirus'' 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'' appearing by the Late Jurassic. While the earliest salamander-line amphibians are known from the Triassic, crown group salamanders first appear during the Middle to Late Jurassic in Eurasia, alongside stem-group relatives. Many Jurassic stem-group salamanders, such as ''Marmorerpeton'' and ''Kokartus'', are thought to have been Neoteny, neotenic. Early representatives of crown group salamanders include ''Chunerpeton, Pangerpeton'' and ''Linglongtriton'' from the Middle to Late Jurassic Yanliao Biota of China. These belong to the Cryptobranchoidea, which contains living Asiatic salamander, Asiatic and giant salamanders. ''Beiyanerpeton'', and ''Qinglongtriton'' from the same biota are thought to be early members of Salamandroidea, the group which contains all other living salamanders. Salamanders dispersed into North America by the end of the Jurassic, as evidenced by ''Iridotriton'', found in the Late Jurassic Morrison Formation. The oldest undisputed stem-caecilian is the Early Jurassic ''Eocaecilia'' from Arizona. The fourth group of lissamphibians, the extinct Albanerpetontidae, albanerpetontids, first appeared in the Middle Jurassic, represented by ''Anoualerpeton, Anoualerpeton priscus'' from the Bathonian of Britain, as well as indeterminate remains from equivalently aged sediments in France and the Anoual Formation of Morocco.Mammaliaformes
Mammaliaformes, having originated from cynodonts at the end of the Triassic, diversified extensively during the Jurassic. Important groups of Jurassic Mammaliaformes include Morganucodonta, Docodonta, Eutriconodonta, Dryolestida, Haramiyida and Multituberculata. 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'' was adapted to aquatic life, similarly to the platypus and otters. Some members of Haramiyida and the eutriconodontan tribe VolaticotheriniMeng, 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 akin to those of flying squirrels, allowing them to glide through the air. The aardvark-like mammal ''Fruitafossor'', of uncertain taxonomy, was likely a specialist on colonial insects, similarly to living anteaters. Australosphenida, a group of mammals possibly related to monotremes, first appeared in the Middle Jurassic of Gondwana. Therian mammals, represented today by living Placentalia, placentals and marsupials, appear during the early Late Jurassic, represented by ''Juramaia,'' a eutherian mammal closer to the ancestry of placentals than marsupials.Electronic supplementary materialFish
Conodonts
The last known species of conodont, a class of Agnatha, jawless fish 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 (Dipnoi) were present in freshwater environments of both hemispheres during the Jurassic. Genera include ''Ceratodus'' and ''Ptychoceratodus'', which are more closely related to living South American lungfish, South American and Protopterus, African lungfish than Australian lungfish, Queensland lungfish, and ''Ferganoceratodus'' from the Jurassic of Asia, which is not closely related to either group of living lungfish. Mawsoniidae, Mawsoniids, a marine and freshwater/brackish group of coelacanths, which first appeared in North America during the Triassic, expanded into Europe and South America by the end of the Jurassic. The marine Latimeriidae, which contains the living coelacanths of the genus ''Latimeria'', were also present in the Jurassic, having originated in the Triassic.Actinopterygii
Ray-finned fish (Actinopterygii) were major components of Jurassic freshwater and marine ecosystems. Archaic "Palaeonisciformes, palaeoniscoid" fish, which were common in both marine and freshwater habitats during the preceding Triassic declined during the Jurassic, being largely replaced by more Derived (phylogenetics), derived actinopterygian lineages. The oldest known Acipenseriformes, the group that contains living sturgeon and paddlefish, are from the Early Jurassic. Amiiformes, Amiiform fish (which today only includes the bowfin) first appeared during the Early Jurassic, represented by ''Caturus'' 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, 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, the only living representatives being gars (Lepisosteidae) were diverse in both freshwater and marine environments. The oldest known representatives of anatomically modern gars appeared during the Upper Jurassic. Stem-group teleosts, 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 and Osteoglossoidei appearing during this time. The Pachycormiformes, a group of marine stem-teleosts, first appeared in the Early Jurassic and included both tuna-like predatory and filter-feeding forms, the latter included the largest bony fish known to have existed: ''Leedsichthys'', 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. 145–175Chondrichthyes
During the Early Jurassic, the shark-like Hybodontiformes, hybodonts, which represented the dominant group of Chondrichthyes, 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 Neoselachii, 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) is ''Antiquaobatis'' from the Pliensbachian of Germany. Jurassic batoids known from complete remains retain a conservative, guitarfish-like morphology. The oldest known Hexanchiformes and carpet sharks (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 Lamniformes, mackerel sharks (Lamniformes) are from the Middle Jurassic, represented by the genus ''Palaeocarcharias'', which has an orectolobiform-like body but shares key similarities in tooth histology with lamniformes, including the absence of orthodentine. The oldest record of angelsharks (Squatiniformes) is ''Pseudorhina'' 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, 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 catsharks. Synechodontiformes, an extinct group of sharks closely related to Neoselachii, were also widespread during the Jurassic. The oldest remains of modern chimaeras are from the Early Jurassic of Europe, with members of the living family Callorhinchidae appearing during the Middle Jurassic. Unlike living chimaeras, these were found in shallow water settings. The closely related ''Squaloraja'' and Myriacanthoidei, 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 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. The Middle to Late Jurassic was a time of major diversification for beetles. Weevils 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 lepidopterans (the group containing butterflies and moths) are known from the Triassic–Jurassic boundary, with wing scales belonging to the suborder Glossata and Micropterigidae-grade moths from the deposits of this age in Germany. Modern representatives of both Dragonfly, dragonflies and Damselfly, damselflies also first appeared during the Jurassic. Although modern representatives are not known until the Cenozoic, ectoparasitic insects thought to represent primitive fleas, belonging to the family Pseudopulicidae, 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 wasp, Parasitoid wasps (Apocrita) 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 (stick insects), Mantophasmatidae, Embioptera (webspinners), and Raphidioptera (snakeflies). Only a handful of records of mites are known from the Jurassic, including ''Jureremus'', an Oribatida, 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. ''Eoplectreurys'' from the Middle Jurassic of China is considered a stem lineage of Synspermiata. The oldest member of the family Archaeidae, ''Patarchaea'', is known from the Middle Jurassic of China. ''Mongolarachne'' 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'' from the Early Jurassic of Germany, of uncertain placement. Eupnoi harvestmen (Opiliones) are known from the Middle Jurassic of China, including members of the family Sclerosomatidae.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. Sessility (motility), Sessile filter feeders 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 reefs and scleractinian coral reefs. Late Jurassic reefs were similar in form to modern reefs but had more microbial carbonates and hypercalcified sponges, and had weak biogenic binding. Reefs sharply declined at the close of the Jurassic, which caused an associated drop in diversity in Decapoda, decapod crustaceans. The earliest planktonic foraminifera, which constitute the suborder Globigerinina, 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. Coccolithophores and dinoflagellates, which had first appeared during the Triassic, radiated during the Early to Middle Jurassic, becoming prominent members of the phytoplankton. Microconchida, Microconchid tube worms, the last remaining order of Tentaculita, a group of animals of uncertain affinities that were convergent on ''Spirorbis'' tube worms, were rare after the Triassic and had become reduced to the single genus ''Punctaconchus,'' which became extinct in the late Bathonian. The oldest known diatom is from Late Jurassic–aged amber from Thailand, assigned to the living genus ''Hemiaulus.''Echinoderms
Crinoids 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 and Millericrinida. Sea urchin, Echinoids (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 Decapoda, decapods. The first true crabs (Crab, Brachyura) are known from the Early Jurassic, with the earliest being ''Eocarcinus, Eocarcinus praecursor'' from the early Pliensbachian of England, which lacked the crab-like morphology (carcinisation) of modern crabs, and Eoprosopon, ''Eoprosopon klugi'' from the late Pliensbachian of Germany, which may belong to the living family Homolodromiidae. Most Jurassic crabs are known only from carapace 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 crabs also first appeared during the Jurassic, with the earliest known being ''Schobertella, Schobertella hoelderi'' from the late Hettangian of Germany. Early hermit crabs are associated with ammonite shells rather than those of gastropods. Glypheidea, 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 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
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