Allocrioceras Heteromorphic Ammonite

with Soft Tissue Preservation

Allocrioceras Cf annulatum

Mollusca, Cephalopoda, Ammonitida, Anisoceratidae

Geological Time: Middle Cretaceous, Cenomanian Stage (~95 million years ago)

Size (25.4 mm = 1 inch): Fossil is 40 mm tall by 18 mm across on a 70 mm by 45 mm matrix

Fossil Site: Lebanese Lagerstatte, Hajula, Lebanon

Code: RS148

Price: Sold


Allocrioceras Heteromorphic Ammonite with Soft Tissue PreservationDescription:Coming from the Cretaceous of Lebanon this is an ammonite known as Allocrioceras. This is one of the heteromorphic ammonites. 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 Heteromorphic Ammonitehad 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 Cretaceous. There are a few preserved internal structures preserved, of which one seems to be a section of orange and pink that has been interpreted as the ctenidium, or gill, and anothet that shows the siphuncule by which the ammonite controlled its depth. Lastly, the start of the living chamber can also be discerned, making for an excellent study specimen whose main features are delineated in the closeup photograph.

Fossils Purchase Information

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Heteromorphic Ammonite


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