Thoracoceras is an extinct orthocerid

Orthocerida

Orthocerida is an order of extinct nautiloid cephalopods also known as the Michelinocerda that lived from the Early Ordovician possibly to the Late Triassic . A fossil found in the Caucasus suggests they may even have survived until the Early Cretaceous...

 genus from the family Kionoceratidae

Kionoceratidae

Kionoceratidae is a family in the Orthocerida, proposed by Hyatt in 1900 for genera characterized by prominent ornamentation in the form of longitudinal ribs, ridges, or lirae, or combinations thereof, sometimes with similar transverse ornament or faint transverse annulations.When Kionoceratidae...

 characterized by orthoconic shells marked by prominent longitudinal rounded grooves separated by angular ridges, each which has a single row of blunt spines along its apex, and having a small submarginal siphuncle

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 Spirula...

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Thoracoceras, named by Fischer De Waldheim in 1844, is found in Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 and Lower Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 sediments

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

 in the U.S., Europe, and Russia. It is closely related to Kionoceras

Kionoceras

Kionoceras is an extinct nautiloid cephalopod genus included in the orthocerid family Kionoceratidae with scattered worldwide distribution from the Middle Ordovician to the Lower Permian. Kionoceratids are orthocerids with prominent longitudinal ornamentation on their shells, sometimes augmented by...

, Ohioceras

Ohioceras

Ohioceras is an extinct suborthochonic nautiloid from the Silurian of Ohio belonging to the orthoceroid family Kionoceratidae.Ohioceras is characterized by a slightly curved longiconic shell with a circular to slightly depressed cross section. The surface is lined with broad, low, longitudinal ribs...

, and Polygrammoceras

Polygrammoceras

Polygrammoceras is an orthoconic nautiloid that lived during the period from the middle Ordovician to the early Devonian in what is now North America and Eurasia....