Toxodon (meaning "bow tooth") is a genus of ungulate from the Miocene to the Early Holocene. It was one of the last members of a group known as the Notoungulata, a group of extinct ungulates from the Americas. It had a stature similar to that of a rhinoceros, though it was unrelated to them.
Toxodon was a member of the notoungulates an ancient ungulate family that is sister group to the perissodactyls, an extant group of ungulates that includes horses, rhinos, and tapirs.
Description[]
Toxodon was large member of Toxodontidae, about 2.7 m (8 ft 10 in) in body length and about 1.5 m (4 ft 11 in) high at the shoulder, with an estimated weight up to 1,415 kg (3,120 lb). Toxodonʹs head was hippopotamus-like. Because of the position of its nasal openings, it is believed that Toxodon had a well-developed snout. Toxodon possessed a large, barrel shaped body. It had short stout legs with plantigrade feet with three functional relatively short toes. The hind limbs are longer and raised higher than the front limbs, giving a sloped appearance to the body. Like horses, it had a stay apparatus allowing the knees to be passively locked while standing.
The vertebrae were equipped with high apophyses, which most likely supported the massive weight and muscles as well as its powerful head. Toxodon had broad jaws which were filled with bow shaped teeth and incisors. The teeth of Toxodon have no roots and are ever-growing (euhypsodont) like those of rodents and lagomorphs, and often exhibit enamel hypoplasia.
Extinction[]
Toxodon became extinct at the beginning of the Holocene as part of the Quaternary extinction event, alongside almost all other large animals in South America. Previous mid-Holocene dates are now thought to be in error. Their extinction was most likely to the result of humans overhunting the megafauna when they arrived into South America.