Geisonocerina is an extinct genus from the carnivorous nautiloid cephalapod order Orthocerida

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...

 that lived in what would be North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, and Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 during the Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 through 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...

 from 449—290 mya, existing for approximately .

Taxonomy

Geisonocerina was named by Foeste (1935) and included in the Geisonoceratidae as part of the Orthocerida where it is listed in Sepkoski (2002).

Morphology

Geisonocerina has an orthoconic shell with transverse lirae and striae that are periodically thickened. Internal features are similar to Geisonoceras wherein the 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...

 is subcentral with short straight necks and connecting rings that expand slightly into the camerae and in which there are annulosiphonate deposits in the more adapical (juvenile)portion of the siphuncle and cameral deposits in the adapical (early) chambers.

Fossil distribution

Geisonoceras has a widespread distribution covering North America, Europe and Asia. A. K. Miller and W.M Furnish described Geisonocerina among a suite of 12 nautiloid genera from the Ordovician of the Black Hills

Black Hills

The Black Hills are a small, isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, USA. Set off from the main body of the Rocky Mountains, the region is something of a geological anomaly—accurately described as an "island of...

, South Dacota. In Europe, Geisonocerina elongatocintum was identified from a 1973 borehole drilled in the Wenlock area of the Welsh borderland to provide a continuous core from the Llanocery-Wenclock boundary.