- Stylemys nebrascensis
- Oligocene Age
- Brule Formation
- White River Badlands Group
- Pennington County, South Dakota
- This specimen measures approx. 8 1/2″ long x 6 5/8″ wide x 2 5/8″ tall. There has been a small amount of restoration, but overall the specimen was approx. 90% complete.
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. The genus was first described in 1851 by Dr. Joseph Leidy. 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. 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.
Turtle or tortoise? It can be very confusing, especially when they belong to the same taxonomic order of Chelonia, which in Greek means tortoise! Basically, tortoises live on land and have short strong legs which they use for support and to dig burrows for protection. Turtles live in water and have webbed feet to help them swim. They will occasionally venture on to land for short periods of time (for example, to lay their eggs), but they will always stay close to water.