''Bitaunioceras'' is a genus of

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

orthocerid Orthocerida, from Ancient Greek ὀρθός (''orthós''), meaning "straight", and κέρας (''kéras''), meaning "horn", also known as the Michelinocerida, is an order of extinct orthoceratoid cephalopods that lived from the Early Ordovician ...

s with a gradually expanding, straight, orthodontic shell with straight transverse sutures and a small, subcentral

siphuncle The siphuncle is a strand of biological tissue, tissue passing longitudinally through the mollusc shell, shell of a cephalopod mollusc. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the li ...

with straight tubular orthochromatic necks. The shell surface of ''Bitaunioceras'' has a few, shallow, rounded constrictions and numerous, unequal, prominent transverse wire-like lirae. ''Bitaunioceras'' species have been found in Texas in the United States, Coahuila in Mexico, Sicily, Timor, and the south Urals in Russia.

References

* Sweet, Walter C. 1964. Nautiloidea-Orthocerida.

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K. Geological Soc of America, and Univ Kansas Press. Prehistoric nautiloid genera {{paleo-nautiloidea-stub