Arsinoitherium belonged to the extinct genus of paenungulate mammals under the extinct order Embrithopoda. The easiest way to recognize an Arsinoitherium was by the horns on its head. A noticeable feature of the Arsinoitherium was the pair of three-foot horns projecting from above the nose and the second pair of tiny, knob-like horns on top of the skull directly behind the more enormous horns. Their larger horns were hollow, and they may have used them to compete with other males and make loud mating calls.
These huge mammals had similar features with rhinos but had more resemblance with present-day elephants. Arsinoitherium is frequently compared to a rhinoceros in terms of appearance. However, its bone structure was more like that of an elephant as it possessed skulls, feet, and hips.
Their twin horns, shaped like knives, could grow up to 2.5 feet in length and sometimes even a little over three feet. One interesting fact about these horns is that they never broke, and experts believe they didn’t break because they were covered in keratin. These mammals were about six feet tall and were as long as 11 feet. They also weighed over 5,500 pounds (around 2500 kg).
Arsinoitherium lived about 56 million to 34 million years ago during the Eocene Epoch. However, more recent discoveries in other locations show that members of the genus survived into the Oligocene Epoch about 34 million to 23 million years ago. Experts in Egypt found the first fossils of the Arsinoitherium. Since these fossils were found around the Faiyum Oasis in Egypt, they decided to name their discovery after Queen Arsinoe I of Ancient Egypt.
2004 saw the discovery of new Arsinoitherium fossils by paleontologists researching in Ethiopia‘s Chilga region. The newly discovered species was named Arsinoitherium giganteus because, based on tooth comparisons, it was almost 25% larger than the initial fossils unearthed. In addition to these noteworthy discoveries, paleontologists have also discovered a number of fossil fragments (primarily teeth) in various regions of Africa and the Middle East that originate from an unidentified species of the genus.
While alive, members of the Arsinoitherium genus were massive, slow-moving mammals. It is generally believed that they, like modern hippos, resided in swamps and semi-aquatic environments. Instead of swinging forward, their forelimbs were designed to pull firmly backwards. This trait is typical of animals that prefer to drag themselves across marshes, sticky soils, and other types of shallow water. As a testament to this, most of the fossils discovered thus far were found in sediments resembling warm, humid lowland forests with dense vegetation or coastal swamp settings. Arsinoitherium preferred to spend time in small groups that spent most of the time in the water. Its inability to straighten its legs implied that it chose to wade and swim rather than walk.
The habitat of Arsinoitherium was disrupted by significant climate change that occurred in the Late Eocene. The temperature changed from being hot to being much more chilly. Due to this, their moist forested environment was lost, and grasslands and savannas began to grow. A few of these mammals survived still and began to change habitats, looking for other parts of the continent that were still warm and had enough food for them. However, by the Middle Oligocene, these animals could no longer move around as much, as most of their food sources had been destroyed. Consequently, they went extinct shortly after this period.
