''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 preserve ...

genus of dry land

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

belonging to the order

Testudines Turtles are reptiles of the order (biology), order 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) and Crypt ...

discovered in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

, and

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, based on fossil distribution. The genus was first described in 1851 by Joseph Leidy. The tortoise was common in the

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

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, ...

, especially

Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...

and

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, 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 Dakota people, Dakota Sioux ...

. The species has also been found in the formations in and around Badlands National Park. Fossil fragments have also been found in the Palm Park Formation of

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. The ancient tortoises had primitive jaw 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 evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

. 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 (from Latin, meaning 'third' or 'of the third degree/order..') may refer to: * Tertiary period, an obsolete geologic period spanning from 66 to 2.6 million years ago * Tertiary (chemistry), a term describing bonding patterns in organic ch ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

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
nps.gov
Testudinidae Cenozoic turtles of North America White River Fauna Prehistoric turtle genera Taxa named by Joseph Leidy Extinct turtles {{paleo-turtle-stub