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| Genus: | Paracymbites Spath, 1925 |
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| Ammonites dennyiSimpson, 1843 | |
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Paracymbites is an extinct genus of lower Jurassic ammonite that lived during Raricostatum zone of upper Sinemurian. Animals belonging to this genus had small shells with semicircular whorl section and rounded or fastigate venter, of which umbilicus made about 25% of diameter. Last whorl could have been excentric. Keel was faint and it might have been only on the earlier part of the last whorl. Aperture had ventral rostrum. Body chamber made about 75% of whorl and was faintly plicate, or smooth. [1] [2]
Fossils belonging to this genus were found in Great Britain, Tunisia and Morocco. [1]
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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 than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appeared during the Devonian, and the last species vanished in the Cretaceous–Paleogene extinction event.
Xipheroceras is a Lower Jurassic ammonite belonging to the Eoderoceratidae, and sometimes placed in the subfamily Xipheroceratinae for which it is the namesake. It has been found in the upper Sinemurian of Europe and possibly Borneo.
Zugodactylites is an extinct genus of ammonite cephalopod from the lower Toarcian epoch of the Lower Jurassic, ammonite zone Fibulatum. Its fossils are found in Europe, Russia and Canada.
Dorsetensia is a narrowly coiled discoidal ammonite from the early Middle Jurassic, lower Bajocian, belonging to the family Sonniniidae of the superfamily Hildoceratoidea. The inner whorls are ribbed or smooth, outer whorl is smooth. The outer rim (venter) is narrow, with a keel running along the middle. The umbilicus, the opening in the middle of the shell exposing inner whorls, is of moderate size with a sharp, sometimes undercut edge.
Placenticeras is a genus of ammonites from the Late Cretaceous. Its fossils have been found in Asia, Europe, North and South America.
Neocomites is a genus of ammonite from the Lower Cretaceous, Berriasian to Hauterivian, and type genus for the Neocomitidae.
Echioceratidae is an extinct family of ammonites that lived during Sinemurian stage of Early Jurassic.
Ophiceras is a genus of smooth, evolute ceratitid ammonites from the Early Triassic, with a rounded venter. Fossils of the genus have been found in Armenia, Azerbaijan, China, Greenland, and India.
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.
Cheltonia is an extinct genus of ammonite from the Upper Sinemurian substage of Lower Jurassic of Europe, Africa, and America. It is probably a microconch of genus Oxynoticeras.
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.
Paroxynoticeras is an extinct genus of lower Jurassic ammonite that lived during upper Sinemurian. Animals belonging to this genus had platyconic shells with compressed whorl section and could grow to large sizes. In the case of young specimens, umbilicum is small, but it increases in bigger specimens.. Last whorl is excentric, which can occur also in relative species, Paracymbites. While on the outer whorls, venter is always rounded, on inner whorls it can be both rounded or sharp. Ornamentation on inner whorls and suture is similar to Oxynoticeras, but in bigger specimens, ribs became straight, simple and blunt. In these bigger specimens, midlateral tubercules might be present.
Slatterites is an extinct genus of lower Jurassic ammonite that lived during upper Sinemurian. Animals belonging to this genus had small shells that had oxycone whorl section and sharp venter when young. In the case of older specimens, whorl section becomes oval and venter is round. This change is very quick. Last whorl is decorated by blunt ribs that can be alternating on opposite sides. Suture is by broad and simple elements similar to suture of Eparietites.
Cymbitidae is family of ammonite that lived during Sinemurian and Pliensbachian stages of Lower Jurassic. They have probably evolved from Arietitidae.
Reynesocoeloceras is genus of ammonite that lived during the lower Pliensbachian stage of early Jurassic, ammonite zones Ibex—Davoei.
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.
Septimaniceras is genus of ammonites that has probably evolved from Peronoceras and lived during the middle Toarcian stage of early Jurassic. 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.
Transicoeloceras, which is sometimes considered to be a synonym of Catacoeloceras is genus of ammonite that lived during Toarcian stage of early Jurassic. Their fossils were found in Hungary, Italy, France, southern Spain and South America. It has evolved from Mesodactylites.
Microdactylites, which is sometimes considered to be a synonym of Dactylioceras, is genus of ammonite that lived during early to middle Toarcian stage of early Jurassic. Their fossils were found in England, France, Italy, Germany and Hungary. Species belonging to this genus were microconchs of Dactylioceras.
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.
