Crioceras sp
Ammonita, Eoduroceratidae
Geological Time: Lower Cretaceous, Hauterivian Stage (~135 million years ago)
Size (25.4 mm = 1 inch): Ammonite is 34 mm across on a 45 mm by 14 mm by 25 mm base
Fossil Site: Montagne de Lute Province, France
Code: RS116
Price: $95.00
 Description:
A fine example of an ammonite of the genus Crioceras of the Hauterivian
Stage (135 m.y.a) deposits of France. It has what is known as heteromorphic
shape. While most ammonites have spiral shells that retain the same
shape throughout growth (homomorph), a major group of ammonites, the
Ancyloceratina,  emerged
during the Late Jurassic which had uncoiled shells instead, and were
called herteromorph ammonites (different-shaped). While little is
known of their mode of life, their uncoiled shells would have precluded
fast swimming. They may have wobbled their way through the water column
with out-splayed tentacles, sweeping whatever came within their reach
into their hungry mouths. As all ammonites, these went extinct at
the end of the Cretaceous. This fine example sits on a matrix pedestal
which has a flattened base for self-display. |
