Thylacoline

Thylacoline (Thylacoline Zealandii) was a species of carnivorous marsupial that was native to New Zealand. Its ancestors had made it into New Zealand because New Zealand was once connected to Australia until 25 million years ago when New Zealand began to break up, causing the isolation of the continent and due to lack of competition (other than eagles) for food, the small carnivorous marsupial grew into gigantic Thylacoleo-like predators. It was the biggest ever carnivorous marsupial to have existed, being about the size of a Siberian tiger. Despite its huge size, it had strong muscles that still allowed it to climb thick trees. It was a strong ambush predator that was big enough to take down its natural food source such as New Zealand giant dylanuses and moa its main food sources. Despite competition with another predator, a Haast's eagle (one of the biggest predatory birds), thylacolines still ruled the forests until humans arrived to New Zealand. They were driven to extinction (along with Haast's eagle) due to overhunting by humans.