Indricotherium: Largest Land Mammal Ever

Indricotherium is an extinct early relative of modern rhinos that lived during the late Oligocene and early Miocene Epochs of the Cenozoic Era. It was also the largest land mammal ever to live on land, at about 25 feet long, 17 feet tall, and weighing nearly 18 tons. In terms of weight, it was four times larger than a modern day bull elephant and rivaled the size of large sauropod dinosaurs that lived during the Mesozoic. Fossils of indricotherium have been unearthed in the Baluchistan province of Pakistan.

Indricotherium was an ungulate (hoofed mammal) that has certain things in common with modern horses and rhinos. It had three hoofed toes on each foot, much like modern rhinos, and had a body in the shape of a bulky horse. Its head was supported by a thick neck that was flexible enough to allow the indricotherium to point its mouth upward to get at hard-to-reach vegetation. Like many Jurassic sauropods, indricotherium was able to reach its titanic size by exploiting a niche that was out of reach of most herbivores. Due to its height, it was able to exclusively browse on the tops of trees nearly twenty feet tall. Its size became its biggest defense against predators, since no mammalian predator of the Oligocene was large enough to bother a full-grown indricotherium. It had two tusk-like front teeth which it used to snip off vegetation which it would then grind with specialized molar-like back teeth. In addition, like modern rhinos, indricotherium had a large, prehensile upper lip that would have aided in stripping vegetation.

During the Oligocene, much of the Earth was covered in dry, seasonal scrublands which could support a variety of large grazing animals as well as large predators. Indricotherium, like other large modern grazing mammals gave birth to a large, single calf. This calf would have needed up to two or three years of care from its mother in order to reach a size large enough to evade predators. A contemporary predator in the Oligocene, hyaenodon, was the size of a rhino and could have easily killed an infant or juvenile indricotherium if given the opportunity.

It is unclear why indricotherium went extinct. The increasing trend toward a drier world through the Cenozoic might have caused the primary food sources of these giant mammals to become extinct. Today, rhinos and horses remain as the legacy of the biggest land mammal ever.