Arsinoitherium is an extinct genus of paenungulate mammals belonging to the extinct orderEmbrithopoda. It is related to elephants, sirenians, hyraxes and the extinct desmostylians. Arsinoitheres were superficially rhinoceros-like herbivores that lived during the late Eocene and the early Oligocene of northern Africa from 36 to 30 million years ago, in areas of tropical rainforest and at the margin of mangrove swamps. A species described in 2004, A. giganteum, lived in Ethiopia about 27 million years ago.
Taxonomy
The best-known species is A. zitteli. Another species, A. giganteum, was discovered in the Ethiopian highlands of Chilga in 2003. The fossil teeth, far larger than those of A. zitteli, date to around 28–27 million years ago. While the Fayum Oasis is the only site where complete skeletons of Arsinoitherium fossils were recovered, arsinoitheriids have been found in southeastern Europe, including Crivadiatherium from Romania, and Hypsamasia and Palaeoamasia from Turkey. The generic nameArsinoitherium comes from PharaohArsinoe I, after whom the Faiyum Oasis, the region in which the fossils were found, was called during Ptolemaic Kingdom, and the θηρίον theríon "beast". The species epithet of the type species, A. zitteli, was given to it in honor of the eminent German paleontologistKarl Alfred Ritter von Zittel, regarded by some as the pioneer of paleontology in Egypt.
Description
When alive, they would have superficially resembled a rhinoceros. Adults of the species A. zitteli stood around tall at the shoulders and in length. The most noticeable features of Arsinoitherium were a pair of enormous horns above the nose and a second pair of tiny knob-like horns over the eyes. Typically portrayed as similar to the ossicones of modern giraffes, they were structurally similar to the horns of modern bovids. The skeleton is robust and the limbs were columnar, similar to those of elephants; the hips were also elephant-like. Arsinoitherium had a full complement of 44 teeth, which is the primitive state of placental mammalian dentition, with characteristics suggesting that it was a selective browser.
Distribution
Fossils of Arsinoitherium have been found in: ;Eocene
