The specimen was important because it preserved several juvenile skeletons inside its pelvic region .
In 1996 Bell and others reported the discovery of a mosasaur of the genus Plioplatecarpus in South Dakota 's Pierre Shale .
The specimen was important because South Dakota preserved several juvenile skeletons inside South Dakota 's pelvic region .
In 1996 Bell and others reported the discovery of a mosasaur of the genus Plioplatecarpus in South Dakota 's Pierre Shale .