What is "haydenoceras"

Haydenoceras is a middle Devonian cephalopod originally placed in the Barrandeocerida. The genus can be recognized by its strongly compressed, gradually expanding exogastrically curved shell with a strongly rounded dorsum and acutely angled venter, calling attention to the general form of earlier Bassleroceras. The siphuncle is tubular, central.

Related genera include Avilionella, Barrandeoceras, '' Gasconsoceras, '' Laureloceras, and Savageoceras.