Ovaticeras
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 (in the case of species "O. ovatum", as "O. paltoides" lived before "Harpoceras falciferum") and died out without leaving any descendants. Description. Compressed, moderately involute shell with keel and narrow venter. Cross section of whorl is elliptical, with rounded umbilical edge and sloping umbilical wall. Falcoid, or sinuous ribs are weak, or  moderate on inner whorls, while on outer whorls, they are becoming striate, or these whorls are smooth. Diameter of complete adult shell is 120–250 mm. Dimorphism is unknown. Species. O. ovatum Most well known and type for this genus. While it is common in Yorkshire, it is rare in other locations. It has several synonyms: O. paltoides Species with softly falcoid ribs. Shell is disc-shaped and involution is hiding 2/5 of previous whorl. It has been found only in Switzerland. Stratigraphical position is unknown. It might come from hawskerense subzone, but it is certainly from before tenuicostatum zone. O.  (Pacificeras) propinquum Subgenus "Pacificeras" is now considered to be synonym of "Tiltoniceras", so this species is now named as "Tiltoniceras propinquum". O. facetum Synonym of "Tiltoniceras propinquum". O. perplexum Synonym of "Neolioceratoides perplexus" . O. mite Synonym of "Parahildaites mitis" .