This is an incredible, museum-quality, fossil Stylemys tortoise (Stylemys nebrascensis)!
This beautiful preparation measures 13" x 11" x 4" and was excavated in Custer County, South Dakota (Brule Formation).
This reptile fossil can be shipped worldwide.
Dating back to ~30 million years before present, these extinct Oligocene reptiles roamed what became the White River Badlands of South Dakota. They were the first fossil genus of dry land tortoise discovered in the USA.