Holcodiscus is an extinct ammonite genus placed in the family Holcodiscidae. Species in this genus were fast-moving nektonic carnivores.[2] The type species of the genus is Ammonites caillaudianus.[2]
Description
Circular to rectangular whorl section; fine, low, straight or flexuous simple or branched ribs, periodically truncated by thin, high, enlarged ribs bearing lateral and ventrolateral tubercles; inner whorls tending to have depressed whorl section and to resemble Olcostephanus.[3]
Fossils of species within this genus have been found in the Cretaceous sediments of Austria, Bulgaria, Chile, Colombia, Czech Republic, Slovakia, France, Italy, Morocco, Spain and Russia.[2]