Caption:
Various dinosaurs of the Hell Creek Formation. Hell Creek Formation is a geologic formation spanning Montana, Wyoming, North Dakota and South Dakota. It dates from the end of the Cretaceous into the early Paleogene. It was a time about 68-66 million years ago. Denizens of this time and place included the ceratopsian; Torosaurus, the hadrosaur; Edmontosaurus, and Tyrannosaurus Rex. An early mammal and possible proto-primate of the time was Purgatorius. It was smaller than a squirrel.