Thylacosmilus (name meaning "pouched saber") is marsupial that had live in Pliocene South America 3 million years ago. They had Saber-Teeth like the Smilodon.
Thought to have been extinct for 2 million years, there are still some that remain alive on Primeval Island. In fact, they are the most common marsupials on the island alongside, Didelphodon and Alphadon.