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Nodicoeloceratinae
The subfamily Nodicoeloceratinae comprises early Jurassic ammonite genera that lived during early to middle Toarcian stage. Origin of this subfamily is unknown, but first genus ''Nodicoeloceras'' has evolved from '' Dactylioceras (Orthodactylites)'' or '' Kedonoceras''. Validity Sometimes, this taxon is considered to be invalid and is included in Dactylioceratinae. This is not so in the case of scientists that describe Mediterranean faunal province that values phylogenetic, morphological and paleobiogeographical importance of this subfamily.M. K. Howarth (2013). Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. Taxonomy Following genera are members of this subfamily: *''Nodicoeloceras'' Buckman, 1926 *''Mesodactylites'' Pinna et Levi-Setti, 1971 *''Transicoeloceras ''Transicoeloceras'', which is sometimes considered to be a synonym of ''Catacoeloceras''M. K. Howarth 2013. Treatise on Invertebrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dactylioceratinae
The subfamily Dactylioceratinae comprises early Jurassic ammonite genera that lived during Upper Pliensbachian to Upper Toarcian stage. These dactylioceratids existed from Margaritatus ammonite Zone, when they have evolved from Reynesocoeloceratinae and died out in Variabilis Zone without leaving any descendants. Description While ribs can be single, they are mostly bifurcating at ventrolateral edge and in some genera, even fibulation (primary ribs are joining at ventrolateral tubercules) can exist. Tubercules might also be present at ventrolateral edge, but not in all species. Final aperture is contracted. Size dimorphism is common. Taxonomy Taxonomic composition of this subfamily differs among literature. Well known is taxonomy according to Treatise on Invertebrate Paleontology, which is shown below with addition of ''Tokurites'', which has not been known in the time, when current edition of Treatise has been published. *''Reynesoceras'' Spath, 1936 *''Dactylioceras'' Hya ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus '' Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. phylogenetic analysis should clearly demons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), 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 (million years ago), and ends at the start of the Middle Jurassic 174.1 Ma. Certain rocks of marine origin of this age in Europe are called "Lias Group, Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic. Origin of the name Lias There are two possible origins for the name Lias: the first reason is it was taken by a geologist from an England, English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north Cornwall, Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonitida
Ammonitida is an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures. Ammonitida is divided into four suborders, the Phylloceratina, Lytoceratina, Ancyloceratina, and Ammonitina. The Phylloceratina is the ancestral stock, derived from the Ceratitida near the end of the Triassic. The Phylloceratina gave rise to the Lytoceratina near the beginning of the Jurassic which in turn gave rise to the highly specialized Ancyloceratina near the end of the Jurassic. Both the Phylloceratina and Lytoceratina gave rise to various stocks combined in the Ammonitina. These four suborders are further divided into different stocks, comprising various families combined into superfamilies. Some like the Hildoceratoidea and Stephanoceratoidea are restricted to the Jurassic. Others like the Hoplitoidea and Acanthoceratoidea are known only from the Cretaceous. Still others like the Perisphinctoidea are found in both. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Age began with the Toarcian turnover, the extinction event that sets its fossil faunas apart from the previous Pliensbachian age. It is believed to have ended with a global cooling event known as the Comptum Cooling Event, although whether it represented a worldwide event is controversial. Stratigraphic definitions The Toarcian takes its name from the city of Thouars, just south of Saumur in the Loire Valley of France. The stage was introduced by French palaeontologist Alcide d'Orbigny in 1842, after examining rock strata of this age in a quarry near Thouars. In Europe this period is represented by the upper part of the Lias. The base of the Toarcian is defined as the place in the stratigraphic record where the ammonite genus '' Eoda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodicoeloceras
''Nodicoeloceras'' is genus of ammonite that lived during early to middle Toarcian stage of early Jurassic. Members of this genus existed from Exaratum Subzone of Falciferum Zone to Commune subzone of Bifrons Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America. It has probably evolved from '' Dactylioceras (Orthodactylites)'' or '' Kedonoceras'' and gave rise to ''Mesodactylites''. Description Ammonites belonging to this genus have moderately evolute to cadicone shells. Whorl section is characterized by depressed whorls with convex flanks and low venter. Ribs are bifurcating at the position of ventrolateral shoulder, where tubercules, or spines are mostly present.Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. Synonyms While ''Mesodactylites ''Mesodactylites'', which is sometimes considered to be a synonym of '' Nodicoeloceras''M. K. Howarth 2013. Treatise on Inver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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's branching ribs. Description ''Dactylioceras'' are generally small, averaging in diameter. They have a strong, ribbed shell. The ribs are slightly inclined forward, running over the outer edge, and either simple or forking at outer end. Though they eventually died out 180 mya, their style of ribbing was copied by numerous subsequent ammonite genera until the whole group became extinct 66 million years ago with the dinosaurs. Ecology ''Dactylioceras'' probably lived by scavenging on the sea floor. Mass mortality specimens of ''Dactylioceras'' are common, and perhaps suggest that these ammonites may often have died shortly after spawning. The dead shells were probably gently washed up into a shell bank on the margins of the Lower Jurassi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesodactylites
''Mesodactylites'', which is sometimes considered to be a synonym of '' Nodicoeloceras''M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus of ammonite that lived during early to middle Toarcian stage (Serpentinum to Bifrons ammonite Zones) of early Jurassic. Their fossils were found in southern and central Europe and northern Africa. It has evolved from ''Nodicoeloceras''. Description Ammonites belonging to this genus have small to medium-sized shells. Coiling is cadicone to moderately evolute. Subcircular whorl section has convex flanks and rounded venter. Ribs can be simple or bifurcating. On ventrolateral position, there are tubercules, mostly on phragmocone The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae. In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transicoeloceras
''Transicoeloceras'', which is sometimes considered to be a synonym of ''Catacoeloceras''M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus of ammonite that lived during Toarcian stage (Bifrons to lower Gradatus ammonite Zones) of early Jurassic. Their fossils were found in Hungary, Italy, France, southern Spain and South America. It has evolved from ''Mesodactylites ''Mesodactylites'', which is sometimes considered to be a synonym of '' Nodicoeloceras''M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus ...''. Description Ammonites belonging to this genus have small shells. Coiling is involute to sphaerocone. Rounded subtrapezoid whorl section has maximum width at the shoulder. Umbilicus is deep and venter is broad and convex. Fine ribs were simple, or bifurcating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telodactylites
''Telodactylites'', which is sometimes considered to be a synonym of ''Porpoceras''M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus of ammonite that lived during Toarcian stage (Gradatus ammonite Zone) of early Jurassic. Their fossils were found in Europe, northern Africa and South America. It has probably evolved from ''Mesodactylites ''Mesodactylites'', which is sometimes considered to be a synonym of '' Nodicoeloceras''M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus ...''. Description Ammonites belonging to this genus have small to medium-sized shells. Coiling is evolute, while whorl section is depressed, subtrapezoidal with oblique flanks and broad and low venter, maximum width is at shoulder. Umbilicus is wide and deep. Sharp, fibulate ribs are dense, tub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collina (ammonite)
''Collina'' is genus of ammonite that lived during lower to upper Toarcian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J .... Members of this genus existed from Braunianus Subzone to Variabilis Zone. Their fossils were found in Europe, Asia, North America and South America. It has evolved from '' Mesodactylites''.Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. Description Whorl section is angular quadrate. Distant ribs can be bifurcating or trifurcating on the place of high ventrolateral tubercules. Secondary ribs are bent strongly forward and raised in the middle part of the venter. Size dimorphism is present in the case of this genus. References Dactylioceratidae Toarcian life Ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
