Dactylioceras was a widespread genus of ammonites from the Lower Jurassic period, approximately 180 million years ago (mya).
Stenopterygius is an extinct genus of thunnosaur ichthyosaur known from Europe. This genus of ichthyosaur grew to a maximum length of 4 meters.
Stephanoceras is an extinct genus of Stephanoceratoid ammonite which lived during the Bajocian. It is the type genus of the family Stephanoceratidae.
Echioceras is an extinct genus of ammonites from the Early Jurassic of Europe and North America.
Harpoceratinae is an extinct subfamily of cephalopods belonging to the family Hildoceratidae. Ammonites of this subfamily had involute and compressed shells with strong keels. Keel might be rarely missing, but this is considered to be an abnormality. This has been observed both in Cleviceras and Harpoceras and called as genus Monestieria, which is now known to be invalid. Another example is Pseudolioceras, whose unkeeled specimen was used as type for description of invalid genus Praehaploceras. Oxyconic forms of this subfamily does not have any keel. Ribs were single, but in some genera also bifurcating with shapes from sigmoidal to falcate. Sometimes, shell can have only striate ribs or is smooth. Tubercules are rare. Dimorphism is known in some genera and it is observable mostly in size. Macrochons can be 4, to 6 times larger than microconchs. As an example, macroconchs of Pseudolioceras are more than 150mm in diameter, while adult microconchs are only 35-50mm. There are big size differences even within dimorphs. Specimens ca be 2, or sometimes even 3 times bigger than other specimens of same dimorph.
Hammatoceras is a genus of ammonites belonging to the family Hammatoceratidae which lived during the Late Toarcian stage of the Early/Lower Jurassic between about 184 and 175 million year ago.
Ovaticeras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during upper Pliensbachian and lower Toarcian. Its fossils were found in Europe, North Africa and possibly also in Canada and Vietnam. It might have evolved from Harpoceras falciferum and died out without leaving any descendants.
Osperleioceras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during Toarcian stage. Its fossils were found in Europe and South America. First species of this genus, Osperleioceras bicarinatum has evolved in what is now France from Harpoceras subplanatum.
Cleviceras is an extinct genus of cephalopod belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during Toarcian and possibly even uppermost Pliensbachian age. Sometimes, it is considered to be a synonym of Eleganticeras.
Radstockiceras is an extinct genus of lower Jurassic ammonite that lived from Oxynotum zone of upper Sinemurian to Raricostatum zone of lower Pliensbachian. Shells of these animals were oxycone and involute with umbilicus that took maximum of 12% of diameter in the case of outer whorls. On inner whorls, venter has been sharp, but then it became rounded. Faint ribs had falcoid shape, but sometimes, ribs could absent. Shells could have been large in their size. Suture has been very complex, similar to Oxynoticeras, but culmination at umbilical margin has been missing. Genus has been named after town of Radstock, in Somerset.
Reynesocoeloceras is genus of ammonite that lived during the lower Pliensbachian stage of early Jurassic, ammonite zones Ibex—Davoei.
Peronoceras is genus of ammonite that lived during the middle Toarcian stage of early Jurassic. Members of this genus existed only in Fibulatum Subzone of Bifrons Zone. Their fossils were found in Europe, northern Africa, Asia, North America and South America.
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. Their fossils were found in Europe, Asia, North America and South America.
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.
Catacoeloceras is genus of ammonite that lived during middle to late Toarcian stage of early Jurassic. Members of this genus existed from Crassum 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 Peronoceras, or Porpoceras.
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.
Mucrodactylites, which is sometimes considered to be a synonym of Collina, is genus of ammonite that lived during middle to late Toarcian stage of early Jurassic. Their fossils were found in Europe, northern Africa and South America. Species belonging to this genus were probably microconchs of Catacoeloceras. As macroconch of M. mucronatus is considered to be Catacoeloceras raquinianum.
Orthildaites is a genus of ammonites that lived during the lower Toarcian stage of early Jurassic, during Falciferum subzone.
Parahildaites is genus of ammonites that lived during the lower Toarcian stage of early Jurassic, during Bifrons zone. It differs from Hildaites and Hildoceras by having smooth shell after reaching 4 cm in diameter. There is no spiral groove and on early whorls, there can be sigmoidal ribs or striae. Strong keel is bordered by flat areas or slight sulci. Its fossils were found in Saudi Arabia and Madagascar.
Mercaticeras is an extinct genus of ammonites belonging to the family Hildoceratidae.
