Dakota, along with neighboring Montana are particularly known
for its dinosaur fossils. The Cretaceous Hell Creek Formation
in Harding County, South Dakota is particularly famous. These
badlands were among those where the famous paleontologists, Cope
and Marsh, held there bone wars. of the American West. Dinosaurs
such as Triceratops and Tyrannosaurus have been discovered there.
Beautiful iridescent scaphites ammonites are found in the Cretaceous
Fox Hills Formation in north central South Dakota. South Dakota
during the during the Cretaceous bordered a vast and shallow
inland sea extending from what is now the Gulf of Mexico well
up into Canada. Ammonites thrived in this sea while huge dinosaurs
roamed the land.