''Anthoceras'' is a genus of straight, annulated,
proterocamerioceratids (Order
Endocerida
Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early Ordovician possibly to the Late Silu ...
) from the
Lower Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya.
The ...
, found in North America, NW Australia, and Siberia. The cross section is circular, the siphuncle moderately large, and marginal. Segments are constricted (producing concave profiles in internal molds); septal necks hemichoantici to subholochoantic (reaching halfway to almost to the previous septum); connecting rings thick. Endocones are long and slightly asymmetric.
This genus is based on the phragmocone, the chambered part of the shell; the apical and apertural ends are unknown.
See also
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References
* Curt Teichert, 1964. Endoceratoidea. Treatise on Invertebrate Paleontology, Part K. Geol Soc. of America and Univ of Kansas press. Teichert and Moore (eds)
*
Prehistoric nautiloid genera
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