Rare Cretaceous Heteromorph Ammonite

Ancyloceras (Audiloceras) Ammonite

Phylum Mollusca, Class Cephalopoda, Subclass Ammonoidea, Order Ammonitida, Family Pleuroceratidae

Geological Time: Cretaceous Barremian Stage (117-113 million year old)

Size: Matrix is 3.1 inches by 2.2 inches

Fossil Site: Agadir, Morocco

Heteromorph AmmoniteComing from the Cretaceous Barremian Stage (117-113 million year old) deposits of Agadir, Morocco, this is an Ancyloceras (Audiloceras) ammonite. It has what is known as heteromorph shape. While most ammonites have spiral sheels that retain the same shape throughout growth (homomorph), a major group of ammonites, the Ancyloceratina, emerged during the Late Jurassic that had uncoiled shells, 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 Creataceous.

See more: Ammonites

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