''Aspinoceras'' is an extinct genus of

heteromorph The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and bec ...

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) ...

s that lived during the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

. The shell small; starts off with a few loosely wound whorls not in contact followed by a short moderately curved shaft ending in a broad hook. Surface covered with mostly fine, close spaced ribs, with periodic larger ribs. In general form it resembles ''

Ancyloceras ''Ancyloceras'' is an extinct genus of heteromorph ammonites found throughout the world during the Lower Cretaceous, from the Lower Barremian epoch until the genus extinction during the Lower Aptian.Sepkoski, JacSepkoski's Online Genus Database � ...

''. ''Aspinoceras'' has been found in upper

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the Va ...

- lower

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

formations in Europe and California.

References

* Ancyloceratoidea Ammonitida genera Early Cretaceous ammonites of North America {{Ammonitida-stub