Toxodon (meaning "bow tooth") is an extinct mammal of the late Pliocene and Pleistocene epochs from about 2.6 million to 16,500 years ago. It is a member of Notoungulata, one of several now extinct orders of hoofed mammals indigenous to South America. It was among the largest and last members of its order, and was probably the most common large-hoofed South American mammal of its time. Analysis of collagen sequences obtained from Toxodon as well as from Macrauchenia found that South America's native notoungulates and litopterns form a sister group to perissodactyls, making them true ungulates.