04944 - Stunning Heteromorph Ammonites Ancyloceras sp 4.57 Inch Lower Cretaceous

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 become one of the most distinctive components of Cretaceous marine faunas. They have been recorded from every continent and many are used as zonal or index fossils. The most distinctive feature of the majority of the Ancyloceratina is the tendency for most of them to have shells that are not regular spirals like most other ammonites. These irregularly-coiled ammonites are called heteromorph ammonites, in contrast to regularly coiled ammonites, which are called homomorph ammonites.

This specimen has been carefully prepared and extracted from its natural limestone rock. It has some fractures that have been glued and restored. However, it is a really beautiful specimen.

Then we leave a link to an interesting reading on the understanding of the paleoecology of these interesting ammonites:

Understanding heteromorph ammonites