Toxodon

Toxodon (name meaning "Bow Tooth") is a genus of Notoungulata that originated during the Late Miocene epoch in what is now South America. A large hippo-like mammal measuring 4 meters long and weighing 2 tons, it was probably the most common large-hoofed mammal in South America at the time of its existence.

In the episode "King of the Cats", a herd of a dozen Toxodon and their babies were lived all of their own lifes from Early Pleistocene South America, 1 million years ago. They reside in the Giraffe Grasslands.

Era & Discovery
Toxodon lived in South America during the Late Miocene to the Middle Holocene epochs, over 11.6 million to 5000 years ago. They were among the largest herbivores of their time, and as such, were prey items along with Macrauchenia for animals like Smilodon and Phorusrhacos. Toxodon became extinct at the end of the Pleistocene when North America and South America met and a migration of more competitive herbivores came about, as well as predators.

In 1837, Charles Darwin was one of the first to collect Toxodon fossils, after paying 18 pence for a T. platensis skull from a farmer in Uruguay. Many Toxodon remains have been found in close proximity to primitive arrowheads, a sure sign that this slow, lumbering beast was hunted to extinction by early humans.

Physical Attributes
Toxodon was a large hippo-like creature that stood more than 6 feet (2 m) tall, measured 10 – 14 feet (3 – 4 m) long, and weighed about 1.5 – 2 tons (3,000 – 4,000 lbs.), making them among the largest animals in South America during their time.

Toxodon is what paleontologists call a "notoungulate", a megafauna mammal closely related to the ungulates (hoofed mammals) but is not quite in the same ballpark. This herbivore evolved to look very much like a modern rhinoceros, with stubby legs, a short neck, and teeth well adapted to eating tough grass (it may also have been equipped with a short, elephant-like proboscis at the end of its snout).

The vertebrae were equipped with high apophyses, which most likely supported the massive weight and muscles as well as its powerful head. But these creatures were so superb, they were so much more like of hippopotamuses, the way the wallowed. Despite their heavy size, Toxodon was a fairly fast mammal for its overall size, enough to keep pace with a Safari Jeep for at least a short time.

English national historian Charles Darwin discovered the fossils of Toxodon when he journeyed to South America sometime in the 1800s. Rather than finding the full skeletons, he only found their skulls instead. And in his own words written in his journal "The Voyage of the Beagle", he wrote:

"Lastly, the Toxodon, perhaps one of the strangest animals ever discovered. In size, it equaled an elephant or megatherium, but the structure of its teeth, as Mr. Owen states, proves indisputably that it was intimately related to the Gnawers, the order which, at the present day, includes most of the smallest quadrupeds. In many details, it is allied to the Pachydermata. Judging from the position of its eyes, ears, and nostrils, it was probably aquatic, like the Dugong and Manatee, to which it is also allied. How wonderfully are the different Orders, at the present time so well separated, blended together in different points of the structure of the Toxodon!"

- Charles Darwin

Behavior & Traits
Toxodon was initially believed to have been an aquatic animal, much like a manatee, dugong, or sea cow. However, after examining the proportions of its femur and tibia, as well as the position of its head, below the top of the spinal column, paleontologists realized that it had features similar to terrestrial animals, such as elephants, rhinos, and hippos. The fossils were also usually found in arid and semi-arid areas, typically an indication of primarily terrestrial life. However, they were indeed related to the hippopotamus.

Toxodon had broad jaws that were filled with bow-shaped teeth and incisors. These teeth would have allowed the animal to tear through and bite off the plants and leaves.

Much like its contemporary Macrauchenia, Toxodon's relationship to living mammals is uncertain. It falls into the larger clade of Notoungulata, literally Southern Ungulates, but the placement of this group within placental mammals is highly uncertain. They maybe have a close relationship with animals in the group Afrotheria but research in mammalian systematics is only beginning to be able to evaluate that, and other hypotheses. Toxodon would have had a very unusual gait, due to its peculiar proportions. It may have galloped to escape predators, but like a rhino, it probably relied more on its size as protection against predators.

Like many herbivorous animals, Toxodon lived and traveled in giant herds. They were also as dangerous as hippos, which are the most dangerous animals in Africa. Toxodon also needed to wallow in the heat of the day, just like hippos, meaning they had something of an amphibious lifestyle.

Trivia

 * The sound effects of Toxodon are that of bear, bison, bull, camel, cow, hippopotamus, rhinoceros, and walrus sound effects.
 * Toxodon was the second-largest South American mammal to be in the museum, the other one is the Megatherium.