Didelphodon vorax

Didelphodon was a metatherian mammal from the Late Cretaceous of North America, and a close relative of marsupials. Didelphodon had a robust skull that combined predatory canines with bulbous crushing molars. It probably ate insects and small vertebrates in its environment, potentially including diving for shellfish or other invertebrates that could be crushed with its molars. While only the size of an opossum, it was still one of the larger mammals alive at the time.