''Gymnites'' is a genus of ammonoid cephalopod from the Middle Triassic belonging to the

ceratitid Ceratitida is an order that contains almost all ammonoid cephalopod genera from the Triassic as well as ancestral forms from the Upper Permian, the exception being the phylloceratids which gave rise to the great diversity of post Triassic ammoni ...

family

Gymnitidae Gymnitidae is a family of Lower to Middle Triassic ammonite cephalopods with evolute, discoidal shells. Hyatt and Smith (1905, p. 114-115) included the Gymnitidae in the suborder Ceratitoidea, which later became the superfamily Ceratitacea ...

. These nektonic carnivores lived during the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

period,

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...

age.Sepkoski, Jac
Sepkoski's Online Genus Database – Cephalopoda
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Species

* ''Gymnites aghdarbandensis'' Krystyn and Tatzreiter 1991 * ''Gymnites asseretoi'' Tozer 1972 * ''Gymnites billingsi'' Bucher 1989 * ''Gymnites calli'' Smith 1914 * ''Gymnites compressus'' Tozer 1994 * ''Gymnites evolutus'' Shevyrev 1995 * ''Gymnites humboldti Mojsisovics 1882 * ''Gymnites incultus'' Beyrich 1867 * ''Gymnites machangpingensis'' Zhao and Wang 1974 * ''Gymnites perplanus'' Meek 1877 * ''Gymnites petilus'' Wang and Chen 1979 * ''Gymnites procerus'' Tozer 1994 * ''Gymnites robinsoni'' Shevyrev 1995 * ''Gymnites toulai'' Arthaber 1914 * ''Gymnites tozeri'' Bucher 1992 * ''Gymnites tregorum'' Silberling and Nichols 1982 * ''Gymnites vastesellatus'' Welter 1915

Description

The shell of ''Gymnites'' is evolute, generally smooth, with a wide umbilicus. Whorls are moderately embracing, whorl section oval and somewhat compressed. The outer whorl may be costate or have rows of nodes, or both. The suture is ammonitic with a wide bifurcated ventral lobe and two lateral lobes on either side.

Taxonomic relation

Hyatt and Smith (1905, p. 115)included ''Gymnites'' in the

along with ''

Ophiceras ''Ophiceras'' is a genus of smooth, evolute Ceratitida, ceratitid Ammonoidea, ammonites from the Early Triassic, with a rounded venter. Fossils of the genus have been found in Armenia, Azerbaijan, China, Greenland, and India.

'', '' Flemingites'', and '' Xenaspis'', genera since assigned elsewhere, and included the Gymnitidae in the suborder Ceratitoidea (now the superfamily

Ceratitaceae Ceratitoidea, formerly Ceratitaceae, is an ammonite superfamily in order Ceratitida characterized in general by highly ornamented or tuberculate shells with ceratitic sutures that may become goniatitic or ammonitic in some offshoots. (Arkell ' ...

). Smith (1932, p. 30) shows ''Gymenites'' derived from ''Xenaspis'' and giving rise to the Pinacoceratidae. The American Treatise (Part L, 1957) also includes ''Gymnites'' in the Gymnitidae, along with mainly descendant forms such as '' Buddhaites'', '' Japonites'', and variations on ''Gymnites'' itself, but instead included the Gymnitidae in the

Pinacocerataceae Pinacoceratoidea, formerly Pinacocerataceae, are generally smooth, compressed, evolute to involute ammonoids from the Triassic, belonging to the Ceratitida, in which the suture is ammonitic, with adventitious and auxiliary elements. As presently ...

which is consistent with Smith's derivation of the Pinacoceratidae from ''Gymnites''.

Distribution

Fossils of species within this genus have been found in the

of Afghanistan, Canada, China, Hungary, Iran, Russia, Switzerland, Turkey, United States.

References

* Alpheus Hyatt and James Perrin Smith, 1905. The Triassic Cephalopod General of America. United States Geological Survey Professional Paper no. 40. *

James Perrin Smith James Perrin Smith (November 27, 1864 – January 1, 1931) was an American geologist and paleontologist. Smith was of English descent. T. M. Forster, one of his ancestors, was a surgeon in the Royal Navy and moved to Virginia in 1745. His paternal ...

, 1932. Lower Triassic Ammonoids of North America. U.S. Geological Survey PP 167. * Treatise on Invertebrate Paleontology, Part L, Ammonoidea. Geol Soc. of America and Univ. Kansas Press, 1957. p. L184. {{Taxonbar, from=Q5624497 Ammonites of Europe Triassic ammonites Anisian life Gymnitidae Ammonite genera