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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 o ... [...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 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eoderoceratoidea
Eoderoceratoidea is a superfamily of true ammonites (suborder Ammonitina) from the Lower Jurassic, comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercles. Adult shell size ranges from 2 or 3 cm to giants reaching 50 cm in such genera as ''Apoderoceras'', '' Epideroceras'', and '' Liparoceras''.Donovan,D.T., Callomon and Howarth 1981. Classification of the Jurassic Ammonitina; Systematics Association. Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press The earliest known eodoceroceratoidean is the eoderoceratid genus '' Microderoceras''. Although its origin is uncertain, it is likely that it is derived from the Psiloceratoidea Psiloceratoidea is a superfamily of Early Jurassic ammonoid cephalopods proposed by Hyatt in 1867, assigned to the order Ammonitida. They were ve ... [...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] |
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] |
Reynesoceras
''Reynesoceras'' is genus of ammonites that lived during the upper Pliensbachian stage of early Jurassic. It has evolved from ''Prodactylioceras'', or '' Cetonoceras''. '' Dactylioceras (Eodactylites)'' has probably evolved from this genus. ''Aveyroniceras'' is a name for macroconchs of this genus. Their fossils were found in Europe, northern Africa, Asia, North America and South America.Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77. Description Ammonites of this genus had shells with depressed whorl section and single, coarse ribs. Ribs are crossing venter, but there is no bifurcation, which is often present on other genera belonging to ''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 involu ...''. Als ... [...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] |
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] |
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] |
Tokurites
''Tokurites'' is a monospecific genus of ammonite that lived during the Toarcian stage of early Jurassic, ammonite zone of Zugodactylites braunianus. Its shell has ribs, which cross the ventral part of the shell creating pricky tubercules there. By these tubercules, it differs from any other member of Dactylioceratidae. This genus is closely related to genus ''Reynesoceras ''Reynesoceras'' is genus of ammonites that lived during the upper Pliensbachian stage of early Jurassic. It has evolved from ''Prodactylioceras'', or '' Cetonoceras''. '' Dactylioceras (Eodactylites)'' has probably evolved from this genus. ''Av ...''. The genus is based on the single specimen with diameter of 15 mm and thus consist from only one species ''Tokurites inopinatus''. This is the only specimen that has been found in the Asian part of Russia. References Dactylioceratidae Toarcian life Ammonites of Asia Fossils of Russia Ammonitida genera {{Ammonitina-stub ... [...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] |
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] |
