Stephanoceras is an extinct genus of Stephanoceratoid ammonite which lived during the Bajocian. It is the type genus of the family Stephanoceratidae.
Aspidoceras is an extinct ammonoid cephalopod genus belonging to the family Aspidoceratidae.
Audaxlytoceras is an extinct genus of lytoceratid ammonites.
Frogdenites is an extinct ammonite genus from the order Ammonitida that lived during the Middle Jurassic in what is now Europe, Canada, and Tibet. Frogdenites is included in the Otoitidae, a family which makes up part of the ammonitid superfamily, Stephanoceratoidea.
Zurcheria is a genus of dwarf ammonites from the Middle Jurassic included in the Hammatoceratidae and lacking a keel. The shell is evolute, inner whorls exposed; whorls compressed and slightly overlapping. Bears ribs, which are sinuous folds that project strongly onto the arched venter.
Lytoceratina is a suborder of Jurassic and Cretaceous ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings.
Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.
Emileia is an extinct genus from a well-known class of fossil cephalopods, the ammonites, that lived during the early part of the Bajocian.
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.
Otoites is the type genus of the ammonite family Otoitidae that live during the Middle Jurassic.
Oecoptychius is an extinct genus of fossil ammonite cephalopods. The species lived during the Middle Jurassic.
Haplopleuroceras is a Middle Jurassic ammonite and likely member of the Hildoceratacean family Sonniniidae with which it shares the same sort of ribbing.
Liparoceras is an extinct fossil ammonite species from the Early Jurassic period of England, and is found in lower Lias deposits. Its name means 'fat head' and this is due to its broad shell. The venter is wide and finely ribbed with no keel and it has two rows of tubercules on each whorl.
Otoidtidae: stephanoceratoid ammonitina from the early Middle Jurassic that begin as cadicones but become more planualte with age; derived from the Hammitoceratidae (Hildoceratoidea), probably through Erycites by way of Abbasites.
Stephanoceratidae is a family of planulate and coronate ammonites within the Stephanoceratoidea. Shells are evolute so that all whorls are exposed and have strong ribbing that bifurcates, that is splits in two, on the flanks. Many have tubercles at the point of bifurcation. Whorl sections are generally subequant; the outer rim, or venter, commonly rounded.
Macrocephalites is a genus of the stephanoceratoid ammonite family Macrocephalitidae, diagnostic of the Callovian stage of the Middle Jurassic. Three subgenera, Dolikephalites, Kamptokephalites, and Pleurocephalites are recognized in addition to Macrocephalites itself, with Indocephalites tentatively included as the fourth.
Microderoceras is a flat sided, evolute, radially ribbed Lower Jurassic ammonite belonging to the ammonitid family Eoderoceratidae and superfamily Eoderoceratoidea. Its whorls are subquadrangular in section; venter on the outer rim, rounded; sides with two rows if distinct spines, tubercles on internal molds, formed at either end of the ribs. The lateral surface of the ribcage is concave toward both sides, the lateral side of the dorsal and the lateral side of the ventral surface. The ribs are divided into six pairs (1-3) of the following types: 2-3 is the only type. In the first type, the ribs on the ventral face are fused to the ribs on the ventral sides; the ribs on the dorsal face are fused to the ribs on the dorsal sides. The second type represents the ribbed body, the ribs are in the same arrangement as in the first type and the rib cage does not fuse to the dorsal surface.
Kepplerites is a moderately evolute ammonite from the lower Callovian included in the Stephanoceratoidea.
Hecticoceras is an ammonite genus belonging to the haploceratoid family Oppeliidae, that lived during the Middle and Late Jurassic, from the Callovian. Hecticoceras may be seen as a series of some nine subgenera, beginning with the lower Callovian H. (Hecticoceras) and H. (Hecticoceratoides) and ending with the lower Oxfordian H. (Pseudobrightia) and H. (Eochetoceras). Hecticocerassensu lato and Prohecticoceras from the underlying Bathonian form the oppeliid subfamily, Hecticoceratinae.
Hammatoceras is a genus of ammonites belonging to the family Hammatoceratidae which lived during the Toarcian stage of the Early/Lower Jurassic between about 184 and 175 million year ago.
