Pachyceras

Pachyceras Temporal range: late Middle Jurassic (Callovian)
Fossil of Pachyceras lalandeanum from Calvados (France), on display at Galerie de paléontologie et d'anatomie comparée in Paris
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Ammonoidea
Order:	Ammonitida
Superfamily:	Perisphinctaceae
Family:	Pachyceratidae
Genus:	Pachyceras Bayle 1878

Pachyceras is a perisphinctoid ammonite genus from the Middle Jurassic, upper Callovian stage, and is the type genus for the family Pachyceratidae. The shell is involute, subglobular, with a deep umbilicus and flattened flanks that slope toward a more narrowly rounded venter, and covered by low, widely spaced ribs.

References

• D. T. Donovan, J. H. Callomon and M. K. Howarth 1981. Classification of the Jurassic Ammonitina; The Ammonoidea. The Systematics Association special volume no. 18