Purgatorius is the genus of the four extinct species believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 65 million years ago. Remains were originally discovered in what is now eastern Montana's (United-States, Hell Creek Formation) Tullock Formation (early Paleocene, Puercan), specifically at Purgatory Hill (hence the animal's name) in deposits believed to be about 63 million years old. It is thought to have been rat-sized at 6 in (15 cm) long and 1.3 ounces (about 37g) and a diurnal insectivore, who burrowed through small holes in the ground.
When Dinosaurs Roamed America
We only see it in one scene in the late Cretaceous segment. After the exinction, a mom and her babies crawl on some T. rex bones. They were live-acted by opposums.