''Stylemys'' (meaning "pillar turtle") is the first

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

genus of dry land

tortoise Tortoises () are reptiles of the family Testudinidae of the order Testudines (Latin: ''tortoise''). Like other turtles, tortoises have a turtle shell, shell to protect from predation and other threats. The shell in tortoises is generally hard, ...

belonging to the order

Testudines Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...

discovered in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. The genus lived in temperate to subtropical areas of North America,

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 Continent#Subcontinents, subcontinent of Eurasia ...

, and

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

, based on fossil distribution. The genus was first described in 1851 by

Joseph Leidy Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist. Leidy was professor of anatomy at the University of Pennsylvania, later was a professor of natural history at Swarthmore ...

. The tortoise was common in the

prehistoric Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of ...

Badlands Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, m ...

, especially

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

and

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

. The species has also been found in the formations in and around

Badlands National Park Badlands National Park ( lkt, Makȟóšiča) is an American national park located in southwestern South Dakota. The park protects of sharply eroded buttes and pinnacles, along with the largest undisturbed mixed grass prairie in the United State ...

. Fossil fragments have also been found in the

Palm Park Formation The Palm Park Formation is a geologic formation in southern New Mexico. It preserves fossils dating back to the Eocene epoch. Description The formation consists of reddish clastic sediments, including some beds of boulder conglomerate with i ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

. The ancient tortoises had primitive

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

muscles, unlike today's tortoises, which also display the '' os transiliens'' bone, and would have been

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

. While ''Stylemys'' species did exhibit the same neck structure as modern tortoises, the forelimbs were unsuitable for burrowing, setting them apart from modern genera.

Species

A number of species have been described since the genus was named in 1851.The Paleobiology Database
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Time period

Eon: Phanerozoic Era: Cenozoic Period: Paleogene Epoch: Eocene *''S. botti'' *''S. calaverensis'' *''S. canetotiana'' *''S. capax'' *''S. conspecta'' *''S. copei'' *''S. emiliae'' *''S. frizaciana'' *''S. karakolensis'' *''S. nebrascensis'' (syn. ''S. amphithorax'') *''S. neglectus'' *''S. oregonensis'' *''S. pygmea'' *''S. uintensis'' *''S. undabuna'' Image:Stylemys_conspecta_01.jpg, ''Stylemys conspecta'' from

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

Image:Stylemys.jpg, ''Stylemys nebrascensis'' shell at the Museum für Naturkunde, Berlin

References

* * * https://web.archive.org/web/20080521150612/http://cumuseum.colorado.edu/Research/Objects/jun06_tortoise.html * http://www.paleoclones.com/item.php?item=929 * http://www.nps.gov/pwr/home/text-versions/feat-JODAFeatureAccessible.html Testudinidae Cenozoic turtles of North America White River Fauna Prehistoric turtle genera Taxa named by Joseph Leidy Extinct turtles {{paleo-turtle-stub