Cranocephalites

Cranocephalites is a Middle Jurassic ammonitid genus named by Spath in 1932 and included in the family Cranoceratidae, superfamily Stephanoceratacea. Cranocephalites, sometimes considered a subgenus of Arctocephalites which has sharply ribbed inner whorls and a smooth outer whorl, has a constricted eccentric body chamber. It is found in middle Jurassic sediments in Alaska, Greenland, Novaya-Zemlya, and eastern Siberia.