''Bitaunioceras'' is a genus of

Permian The Permian ( ) is a geologic period and 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 251.9 Mya. It is the last period of the Pale ...

orthocerid Orthocerida is an order of extinct Orthoceratoid cephalopods also known as the Michelinocerida that lived from the Early Ordovician () possibly to the Late Triassic (). A fossil found in the Caucasus suggests they may even have survived until t ...

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

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

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'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

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