Name: Ammonita; Pleuroceratidae; Audoliceras sp.
Geological Age: Cretaceous Aptian Stage (~120 million years ago)
Size (25.4 mm = 1 inch): 190 mm across on a 190 mm by 240 mm base.
Location: Volga River Region, Saratov, Russia
Code: RA376
Price: $450.00 - sold
 Description:
A superb large example of an ammonite of the genus Audoliceras of
the Aptian Stage (120 m.y.a) deposits of Russia. It has what is known
as heteromorph 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
that had uncoiled shells instead, and were called heteromorph 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 has been removed from its friable chalky matrix
and placed in this more durable type for a long-lasting display. |
