Arsinoitherium

Taxobox
name = Arsinoitherium
fossil_range = Late Eocene - Early Oligocene
status = Fossil

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image_width = 240px
image_caption = "Arsinoitherium zitteli"
regnum = Animalia
phylum = Chordata
classis = Mammalia
superordo = Paenungulata
ordo = †Embrithopoda
familia = †Arsinoitheriidae
genus = "†Arsinoitherium"
subdivision_ranks = Species
subdivision =
* "†A. zitteli" Beadnell, 1902
* "†A. giganteus" Sanders, Kappelman & Rasmussen, 2004

"Arsinoitherium" is an extinct genus of paenungulate mammal related to elephants, and hyraxes (Embrithopoda). These species are rhinoceros-like herbivores that lived during the late Eocene and the early Oligocene, from 36 to 30 million years ago in areas of tropical rainforest, and at the margin of swamps.

Appearance and Anatomy

When alive, it would have superficially resembled a rhinoceros, and have been about 1.8 meters tall at the shoulders, and 3 meters long. The most noticeable feature of "Arsinoitherium" was a pair of enormous knife-like horns with cores of solid bone that projected from above the nose, [Alan Turner & Mauricio Anton: "Evolving Eden, An Illustrated Guide to the Evolution of the African Large-Mammal Fauna" (p. 111). Columbia University Press, New York 2004 ISBN 0-231-11944-5] and a second pair of tiny, knob-like horns on top of the head, immediately behind the larger horns. The skeleton is robust, but show that it was descended from a cursorial ancestor, and that the beast may have been able to run if it had to, [Alan Turner & Mauricio Anton: "Evolving Eden, An Illustrated Guide to the Evolution of the African Large-Mammal Fauna" (p. 111). Columbia University Press, New York 2004 ISBN 0-231-11944-5] like a modern elephant or rhinoceros. Its limb bones also suggest that the columnar legs of the living animal were elephant-like (especially since they ended in five-toed feet), rather than rhinoceros-like. "Arsinoitherium" had a full complement of 44 teeth, which is the primitive state of placental mammalian dentition, suggesting that it was a selective browser. The large size and hefty build of "Arsinoitherium" would have rendered it largely immune to predation. However, creodonts may have preyed on the young or infirm.

Etymology

The name derives from Arsinoë, a Ptolemaic Egyptian queen whose palace was near the site of discovery. While this was the only site where complete skeletons of "Arsinoitherium" fossils were found, remnants of earlier relatives lived in south-eastern Europe and Mongolia, in the form of jaw fragments. These earlier arsinoitheres have yet to be formally described. The best known, and first described species is "A. zitteli". A second species, "A. giganteum", was discovered in Ethiopian highlands in 2003. The fossils date back to around 27 million years ago. The height at the shoulder is around 7 feet. The Mongolian material has been named "Radinskya yupingae", while the European material has been given the "nomen dubium" of "Crivadiatherium iliescui", and the Turkish material has been named "Palaeoamasia kansui" (also "nomen dubium").

pecies

*Genus "Arsinoitherium"
**"Arsinoitherium andrewsii" - Egypt
**"Arsinoitherium giganteum" - Ethiopia
**"Arsinoitherium zitteli" - Egypt, Libya, Angola, Oman

Popular culture

In the book, "The Macmillan Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals", the authors erroneously claim that the larger pair of horns of "Arsinoitherium" were hollow and cone-like, [Dixon, Dougal, et al. The Macmillan Illustrated Encyclopedia of Dinosaurs. A Visual Who's Who of Prehistoric Life. Pg. 237. New York: Macmillan Publishing Company. 1988.] a claim which was repeated in the later edition, "The Simon & Schuster Encyclopedia of Dinosaurs & Prehistoric Creatures. A Visual Who's Who of Prehistoric Life" [Palmer, Douglas Ed. The Simon & Schuster Encyclopedia of Dinosaurs & Prehistoric Creatures. A Visual Who's Who of Prehistoric Life. Pg. 237. Great Britain: Marshall Editions Development Limited. 1999.] would be used by Tim Haines and Paul Chambers bolster their claim in their book, "The Complete Guide to Prehistoric Life", that "Arsinoitherium" used its hollow horns as a sound resonator, [Haines, Tim, and Paul Chambers. The Complete Guide to Prehistoric Life. Pg. 164. Canada: Firefly Books Ltd. 2006.] much in the same manner the crests of lambeosaurine dinosaurs, such as "Parasaurolophus", are believed to have been used.

"Arsinoitherium" briefly appears in a 2003 BBC documentary called Sea Monsters, produced by Tim Haines and Paul Chambers (stills from "Sea Monsters" were used for the illustrations of "Arsinoitherium" in "The Complete Guide to Prehistoric Life").

References

External links

* [http://news-info.wustl.edu/news/page/normal/575.html New fossils from Ethiopia open a window on Africa's 'missing years']