This is a real fossil Oreodont (Merycoidodon gracilis) jaw from the Brule Formation in South Dakota. It was once on display at the Hobberlin Museum.
This extinct family of even-toed ungulates were generally hog-like in appearance but more closely related to camels. They ranged from sheep to cattle size and were primarily grassland browsers.
This ~3.75" long specimen is roughly 32 million years old and can be shipped worldwide!