Stylemys

Superregnum: Eukaryota
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Cladus: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Cladus: Archelosauria
Division: Pan-Testudines
Division: Testudinata
Ordo: Testudines
Subordo: Cryptodira
Superfamilia: Testudinoidea

Familia: Testudinidae
Genus: †Stylemys
Species: †

S. botti –

†

S. calaverensis –

†

S. canetotiana –

†

S. capax –

†

S. conspecta –

†

S. copei –

†

S. emiliae –

†

S. frizaciana –

†

S. karakolensis –

†

S. nebrascensis –

†

S. neglectus –

†

S. oregonensis –

†

S. pygmea –

†

S. uintensis –

†

S. undabuna

Stylemys (meaning "pillar turtle") is the first fossil genus of dry land tortoise belonging to the order Testudines discovered in the United States. The genus lived in temperate to subtropical areas of North America, Europe, and Asia, based on fossil distribution.[1] The genus was first described in 1851 by Joseph Leidy.[2] The tortoise was common in the prehistoric Badlands, especially Nebraska and South Dakota. 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.[3]

The ancient tortoises had primitive jaw muscles, unlike today's tortoises, which also display the os transiliens bone, and would have been herbivorous. 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.[4]
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

Stylemys conspecta from Tertiary in Oregon

Stylemys nebrascensis shell at the Museum für Naturkunde, Berlin

References

Auffenberg, Walter (1964). "A Redefinition of the Fossil Tortoise Genus Stylemys Leidy". Journal of Paleontology. 38 (2): 316–324. JSTOR 1301552.
Leidy, J. (1851). "Description of Stylemys nebrascensis". Proc. Acad. Nat. Sci. Phila. 5: 172–173.
Lucas, Spencer G.; Williamson, Thomas E. (1993). "Eocene vertebrates and late Laramide stratigraphy of New Mexico". New Mexico Museum of Natural History and Science Bulletin. 2: 145–157. Retrieved 2 August 2020.

The Paleobiology Database

Garcia, Frank A.; Miller, Donald S.; Burns, Jasper (1998). Discovering Fossils: How to Find and Identify Remains of the Prehistoric Past. Fossils & Dinosaurs. ISBN 0-8117-2800-5.
Case, Gerard Ramon (1992). A Pictorial Guide to Fossils. ISBN 0-89464-678-8.
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