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.

Selected species

Ancyloceras ammonites have a shell reaching a length of about and a width of about. They are known as heteromorph shaped, with a partly uncoiled shell and the aperture directed toward the coiled part.
Most ammonites are homomorph, as they maintain the same shape throughout the growth, while the ammonites in this genus have uncoiled shells, that would have precluded fast swimming.

Distribution

Fossils of Ancyloceras species are found in the Cretaceous Barremian Stage marine strata of Europe and Morocco.