''Cyrtoceras'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

oncocerida The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous; one possible member is known from the Early Permian), in which the connecting rings are ...

nautiloid Nautiloids are a group of marine cephalopods ( Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and '' Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded speci ...

s that lived from the middle

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. ...

to the middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

, in

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...

, North America and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

References

Sources

*''Fossils'' (Smithsonian Handbooks) by David Ward *''Fossils'' (A Golden Guide from St. Martin's Press) by Frank H. T. Rhodes, Paul R. Shaffer, Herbert S. Zim, and Raymond Perlman *''Aquagenesis: The Origin and Evolution of Life in the Sea'' by Richard Ellis

External links

''Cyrtoceras''
in the Paleobiology Database Prehistoric nautiloid genera Devonian cephalopods Ordovician cephalopods Paleozoic cephalopods of Africa Paleozoic cephalopods of Europe Paleozoic cephalopods of North America Paleozoic cephalopods of South America Silurian cephalopods Middle Ordovician genus first appearances Middle Devonian genus extinctions Fossils of Georgia (U.S. state) Paleozoic life of Manitoba Paleozoic life of Nunavut {{paleo-Nautiloidea-stub