Aeogocrioceras spathi
Ammonita, Ancyloceratidae
Geological Time: Lower Cretaceous, Hauterivian Stage (~135 million years ago)
Size (25.4 mm = 1 inch): 62 mm across by 52 mm tall
Fossil Site: Resse Pit, Hannover, Germany
Code: GF09
Price: Sold
 Description:
A fine example of an ammonite of the genus Aegocrioceras of the Hauterivian
Stage (135 m.y.a) deposits of Germany. 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 which had uncoiled
shells instead, and were called  heteromorph
ammonites (different-shaped). This one has the cyrtocone
form in which the coils do not touch, forming an open spiral. 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. |
