Inflated, 8.4" Fossil Tortoise (Stylemys) - South Dakota
This is a nice, 8.4" long specimen of an Oligocene aged tortoise of the genus Stylemys collected from the White River Formation of South Dakota. It is very inflated, not highly crushed like many specimens.
Stylemys ("pillar turtle") is the first fossil genus of dry land tortoise discovered in the United States. The genus lived in temperate to subtropical areas of North America, Europe, and Asia
These extinct 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.