Olcostephanus

Olcostephanus is an extinct ammonoid cephalopod genus belonging to the family Olcostephanidae. These fast-moving nektonic carnivores lived during the Cretaceous, from the upper Valanginian to the lower Hauterivian age.
Distribution.
Fossils of species within this genus have been found in the Cretaceous sediments of Antarctica, Argentina, Austria, Bulgaria, Chile, Colombia (Macanal Formation, Eastern Ranges), Czech Republic, France, Hungary, Italy, Mexico, Morocco, Poland, Portugal, Romania, Slovakia, South Africa, Spain, Russia, United States, as well as in the Jurassic of Argentina.