|
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] |
Dactylioceratidae
The family Dactylioceratidae comprises Early Jurassic ammonite genera with ribbed and commonly tuberculate shells that resembled later Middle Jurassic stephanoceratids and Upper Jurassic perisphinctids. Shells may be either evolute or involute. Description Ammonites with evolute, serpenticone to cadicone shells with ribs, sometimes with tubercules. Members of this family had no keels. while homeomorphic with stephanoceratids and perisphinctids, they had unique shell structure with double shells and flat-topped ribs on the inner shell. Based on suture differences, they are divided into 2 subfamilies. Reynesocoeloceratinae possess two major secondary lobes in dorsal side of external saddle. This saddle is not divided this way in Dactylioceratinae, while lateral lobe is deeply trifid. Evolution It has been suggested, that this family is polyphyletic, but this is now considered to be false. Reynesocoeloceratinae evolved in lower Pliensbachian from '' Metaderoceras'' and died ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reynesocoeloceratinae
The subfamily Reynesocoeloceratinae comprises early Jurassic ammonite genera that lived during Pliensbachian stage. These dactylioceratids existed from Ibex ammonite zone and died out in Spinatum zone. They have evolved from '' Metaderoceras'' and gave rise to subfamily Dactylioceratinae. Description Ammonites with depressed, cadicone, or even evolute, serpenticone shells. Tubercules might be present. Ribs can be both single, or bifurcating. Some members of this subfamily show size dimorphism. They differs from Dactylioceratinae by suture. While Reynesocoeloceratinae has on dorsal side of external lobe two major secondary lobes, this is not so in Dactylioceratinae, as there is external saddle not divided, while lateral lobe is strongly trifid. Taxonomy *Reynesocoeloceratinae Dommergues, 1986 **''Reynesocoeloceras'' Géczy, 1976 **''Bettoniceras'' Wiedenmayer, 1977 **''Prodactylioceras'' Spath, 1923 **''Cetonoceras ''Cetonoceras'' is genus of ammonite that lived during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
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] |
Porpoceras
''Porpoceras'' is genus of ammonite that lived during the early and middle Toarcian stage of early Jurassic. Members of this genus existed from uppermost part of the ''Harpoceras serpentinum'' zone to the '' Haugia variabilis'' zone.Jattiot, R., Fara, E., Brayard, A., & Vennin, E. (2016). Revised stratigraphic range of the Toarcian ammonite genus Porpoceras Buckman, 1911. Geodiversitas, 38(4), 505-513. Their fossils were found in Europe, Asia, North America and South America. Description Ammonites belonging to this genus have evolute shells, with compressed to depressed whorl section. Flanks were slightly convex and venter has been low. Whorl section is subrectangular. Prorsiradiate ribs are strong and fibulate on inner whorls and tuberculate to spined on the place of ventrolateral shoulder.KOVÁCS, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. It differs from '' Peronoceras'' by not having compressed whorl section and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toarcian Life
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] |
Pliensbachian Life
The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 190.8 ± 1.5 Ma and 182.7 ± 1.5 Ma (million years ago). The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian. The Pliensbachian ended with the extinction event called the Toarcian turnover. During the Pliensbachian, the middle part of the Lias was deposited in Europe. The Pliensbachian is roughly coeval with the Charmouthian regional stage of North America. Stratigraphic definitions The Pliensbachian takes its name from the hamlet of Pliensbach in the community of Zell unter Aichelberg in the Swabian Alb, some 30 km east of Stuttgart in Germany. The name was introduced into scientific literature by German palaeontologist Albert Oppel in 1858. The base of the Pliensbachian is at the first appearances of the ammonite species '' Bifericeras donovani'' and genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucrodactylites
''Mucrodactylites'', which is sometimes considered to be a synonym of '' Collina'',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 middle to late Toarcian stage (Bifrons Subzone to lower Variabilis ammonite Zone) of early Jurassic. Their fossils were found in Europe, northern Africa and South America. Species belonging to this genus were probably microconchs of ''Catacoeloceras ''Catacoeloceras'' is a genus of ammonite that lived during Middle Toarcian stage of early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earl ...''. As macroconch of ''M. mucronatus'' is considered to be ''Catacoeloceras raquinianum''. Description Ammonites belonging to this genus have small, evolute and compressed shells with suboval to subquadrate whorl sectio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdactylites
''Microdactylites'', which is sometimes considered to be a synonym of '' Dactylioceras'',M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea. is genus of 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) ... that lived during early to middle Toarcian stage (Serpentinum to lower Bifrons ammonite Zones) of early Jurassic. Their fossils were found in England, France, Italy, Germany and Hungary. Species belonging to this genus were microconchs of ''Dactylioceras''. Description Ammonites belonging to ''Microdactylites'' have small shells with evolute, compressed coiling. Flanks are slightly convex to convex and whorl section is suboval to subcircular. Ribbing is dense, while ribs can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collina (ammonite)
''Collina'' is genus of 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) ... that lived during lower to upper Toarcian stage of early Jurassic. 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 Ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catacoeloceras
''Catacoeloceras'' is a genus of ammonite that lived during Middle 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 Bifrons Subzone of Bifrons Zone to Variabilis Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America. It has evolved from '' Porpoceras''.Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. Description Ammonites belonging to this genus have cadicone shells with depressed, rounded whorl section. Some species have almost sphaeroconic shells and these ones were designated as genus '' Transicoeloceras'', which is considered to be a synonym of ''Catacoeloceras'' by some authors, while sometimes it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Septimaniceras
''Septimaniceras'' is genus of ammonites that has probably evolved from '' Peronoceras'' and lived during the middle 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 Bifrons Subzone to lower part of Variabilis Subzone. Their fossils were found in France, Hungary and probably also in Austria.KOVÁCS, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. Description Ammonites belonging to this genus have evolute shells of small size. Inner whorls are cadicone, while outer whorls are subquadrate. On younger whorls, ribs are widely spaced and are of 2 types. Bold ribs have large ventrolateral tubercules, while fine striate ribs exist between them. Later, single and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
