Abbasites is an extinct genus of ammonites from the early Middle Jurassic epoch, included in the ammonitid family Erycitidae.
Asthenoceras is a genus of ammonoid from the Middle Jurassic with dwarfish, evolute, smooth, compressed, discoidal, strongly keeled shell. Asthenoceras belongs to the Sonniniidae and may be a subgenus of the Lower Jurassic Grammoceras.
Arnioceras is an extinct genus of large, evolute, discoidal ammonite from the Lower Jurassic. The shell is normally coiled so that all whorls are exposed. Sides bear strong sharp ribs that are straight until reaching the ventrolateral edge where they swing forward and fade. The rim (venter) is keeled and free of grooves.
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.
Fontannesia is an ammonoid cephalopod genus with a small to medium size, evolute, discoidal shell that was extant during the Jurassic Period. The sides are ribbed, the venter has a single median keel, and tubercles are lacking.
Newmarracarroceras is an ammonite from the early middle Jurassic with a ribbed subinvolute shell with a keel running along the venter, or outer rim. The umbilicus is moderately wide, exposing the inner whorls exposed in part.
Lissoceras is an involute, smooth or finely vetrolaterally ribbed, ammonite with a blunt, un-keeled venter, included in the Haploceratidae, that lived from the Lower Bajocian - Middle Oxfordian in what is now Europe, south Asia, and southern Alaska.
Hebetoxyites is a genus of ammonoid cephalopod from the middle part of the Bajocian stage, middle Jurassic, included in the Strigoceratidae, Haploceratoidea. The shell is oxyconic, with a sharp rim but no keel, and involute, with the inner whorls hidden. The umbilicus is very small. Sides have a spiral ridge but are not striate.
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.
Arietitidae is a family of true ammonites that make up part of the superfamily Psiloceratoidea, named after the type genus Arietites. They comprise medium-size to large or gigantic genera which in general are strongly ribbed, tuberculate in some, with keeled or grooved and keeled venters, and well differentiated ammonitic sutures. The aptycus is single valved with a shiny, concentrically striated surface.
Amaltheidae is a family of eoderoceratoidean ammonitids from the Lower Jurassic consisting of genera characterised by stigated discoidal oxycones—narrow involute shells with narrowly rounded to angular venters that bear a series of grooves, or ridges, along broad flanks, which according to the Treatise L, 1957, evolved into strongly ribbed planulates with quadrate whorls, typically with crenulated keels; involving all together four genera.
Distichoceras is a member of the Haploceratacean family, Oppeliidae, and type genus for the subfamily Distichoceratinae, found in upper Middle and lower Upper Jurassic sediments in Europe, Algeria, India, and Madagascar. The shell is essentially evolute and compressed with the outer flanks converging on a narrow, keeled venter; inner flanks which may be feebly ribbed, are separated from outer by a shallow spiral groove or band. Ribs on outer flanks end on or are looped to tall clavi that line the venter, standing above the keel.
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.
Grammoceras is an extinct genus of ammonite found in Yorks Ravenscar, England, from Jurassic period sediments. Its overall distribution is fairly worldwide.
Ochetoceras is a genus of ammonites, belonging to the Oppeliidae, that lived during the Late Jurassic from the early Oxfordian to the early Tithonian, and type for the subfamily Ochetoceratinae.
The Ochetoceratinae is a subfamily within the Oppeliidae from the Upper Jurassic, shells of which are typically oxycones with a tricarinate venter and falcoid ribbing, commonly divided by a median lateral groove or fillet. The median (middle) keel is the tallest.
Cymaceras is a genus within the oppeliid subfamily Ochetoceratinae from the Kimmeridgian stage, around the middle of the Upper Jurassic.
Oxydiscites is a genus of ammonites from the Upper Jurassic Kimmeridgian included in the Ochetoceratinae, Oppeliidae. The shell is involute, compressed, with a minute umbilicus, sharp venter with a tall finely toothed keel, and faloid ribbing.
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.
