PIX4664378: Thylacosmilus - Thylacosmilus atrox was a great predator with sword teeth close to marsupials, the size of a jaguar and weighing nearly 100 kilograms, who lived for about 30 million years until three million years ago. About the size of a jaguar, the bizarre looking Pliocene Argentinian marsupial carnivore, Thylacosmilus atrox, is a superb example of the concept of convergent evolution - descendents of unrelated organisms presumably under similar selection pressures “” converging”” on each other in form over time. Its skull looks remarkably like those of placental sabre-toothed cats, to which it was only distantly related. Key differences, however, did exist (e.g. long, rudder-like extensions of the chin protected the extremely long, dagger-like teeth) / Bridgeman Images