Wikipedia
Pachydesmoceras
Pachydesmoceras is a genus of ammonites belonging to the family Desmoceratidae.
Species of this genus were fast-moving nektonic carnivorous shelled cephalopods. They lived during the Cretaceous, from the Albian (112.0-99.6 Mya) to the Santonian (85.8-83.5 Mya) stage.