Thylacosmilus atrox Pillow

In the 1920s Captain Marshall Field funded two expeditions to South America which were undertaken by the Field Museum of Natural History in Chicago, Illinois; these expeditions were launched under the hopes of finding fossils of mammals and other animals from the Cenozoic Era. In 1926, during the second expedition, a team was searching the Ituzaingo Formation in northern Argentina when they came across the remains of three animals thought to be never before discovered species of ancient marsupial. It was roughly 4.9 feet in length and weighed around 330 pounds and it lived during the Late Miocene to Pliocene, roughly 9 to 3 million years ago.