''Aspidostephanus'' is an extinct cephalopod genus belonging to the

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

subclass, included in the perisphinctacean family

Olcostephanidae Olcostephanidae is an extinct ammonoid cephalopod family belonging to the superfamily Perisphinctoidea. These fast-moving nektonic carnivores lived from the Jurassic to the Cretaceous period. Genera *'' Bihenduloceras'' *'' Olcostephanus'' Neuma ...

that lived during the earliest Cretaceous and possible latest Jurassic. Fossils of the genus have been found in France, the Balearics, North Africa, and Argentina. The shell of ''Aspidostephanus'' is depressed with a broad smooth venter. Early whorls have strong lateral ribs with umbilical and lateral tubercles; later whorls smooth except for tubercles at the umbilicus. Whorl height increases with age. ''Aspidostephanus'' is similar to but broader than its close relative, '' Spiticeras''.

References

* Jurassic ammonites Cretaceous ammonites Fossils of Argentina Tithonian first appearances Early Cretaceous genus extinctions Cretaceous Argentina {{ammonite-stub