Mammals of Australia introductions of placental mammals into Australian fauna were about (rats), several thousand years ago (dingo), and 200 years ago (many species); the last two were made by humans. Some claims were made about placental mammal fossils from the Eocene of Australia, called "Tingamarra". These claims are based on only one found tooth having some characteristic features of condylarth, and were discussed widely. But both the age and placental nature of these fossils were challenged by other researchers. Monotremes are mammals with a unique method of reproduction: they lay eggs instead of giving birth to live young. Two of the five
Patagonia (mammal) as opposed to earlier forest environments in the region. This coincides with "Patagonia"'s burrowing, grazing habits. A large variety of mammal species are known, including caviomorph rodents such as "Dudumus", as well as the rodent-like argyrolagoidean paucituberculates. "Patagonia" likely avoided competition in its fairly specialised niche. Patagonia (mammal) Patagonia is an extinct genus of non-placental mammal from the Miocene of Argentina. Traditionally considered a metatherian "incertae sedis", more recent analysis have shown it to be a gondwanathere. It is the youngest allothere species known. Currently, a single species is known, "P. peregrina", hailing from the Colhuehuapian-dating deposits of the Sarmiento