Megistotherium
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| Megistotherium Fossil range: early Miocene |
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 Megistotherium osteothlastes
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Megistotherium osteothlastes (from Greek, Megistos "Greatest" + Therios "Beast") was an enormous hyaenodontid creodont that lived during the early Miocene Epoch some 24 million years ago and is one of the largest terrestrial carnivorous mammals that ever existed. It was named by Robert Savage in 1973. Fossils have been found in Egypt and Libya and it was certainly the largest predatory land mammal ever known to have lived in Africa. It was larger than a bison, over 5-6 meters long (about 16-18 feet) and weighed an estimated 1500 kg, and had a skull that was estimated to be over 1 meter (slightly over 3 feet). Megistotherium may have rivaled Andrewsarchus mongoliensis in size and some argue was the largest mammalian land predator of all time.
The carnassial teeth of Megistotherium (like those of other Creodonta) were the upper first molars, and overlapped with their lower molar counterparts like scissors to form a formidable and powerful shearing action. Although its huge size means that it could not have been very agile, it could certainly take down very large prey. Although Megistotherium is thought to have been a predator, it may have occasionally done some scavenging. The land that is now the Sahara desert was much more fertile in the Miocene. A considerable amount of it was grassland and rainfall was plentiful. Lakes and ponds provided water for the fauna. Megistotherium and other predators had an ample supply of prey.
Mastodon bones have been found with its fossils and this indicates that Megistotherium may have hunted small mastodons for food. Megistotherium was the largest of the creodonts; however, it was probably not the largest carnivorous land mammal.
[edit] Taxonomy
The order Creodonta compromised a diverse group of predators that were most successful during the Eocene before being ecologically displaced by the order Carnivora during the late Oligocene. Megistotherium emerged in the Miocene towards the end of the creodents flourishing; it was a part of a radiation of African hyaenodontids that was occuring at that time. Hyainailouros sulzeri is a close relative of Megistotherium, very similar in size and structure - with a long tail, short limbs and robust body. Some experts suggest that Megistotherium should be placed inside the genus Hyainailouros.
[edit] References
- Domning, D.P. (1978). "Sirenia." Evolution of African Mammals. pp. 573-581.
- Egi, Naoko. (2001). "Body Mass Estimates in Extinct Mammals from Limb Bone Dimensions: the Case of North American Hyaenodontids." Palaeontology. Vol. 44, Issue 3, Page 497.
- Leakey, L.S.B. and R.J.G. Savage (Editors). (1976). Fossil Vertebrates of Africa. Academic Press Inc.,U.S. ISBN-10: 0124404049.
- Rasmussen, D. Tab, Christopher D. Tilden, and Elwyn L. Simons. (1989). "New Specimens of the Giant Creodont Megistotherium (Hyaenodontidae) from Moghara, Egypt." Journal of Mammalogy, Vol. 70, No. 2, pp. 442-447.
- Savage, R.J.G. (1973). "Megistotherium, gigantic hyaenodont from Miocene of Gebel Zelten, Libya." Bulletin of the British Museum (Natural History) 22(7):485-511.
