Megistotherium
| Megistotherium Temporal range: early Miocene 23.03–11.61 Ma |
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| Megistotherium osteothlastes | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Eutheria |
| Superorder: | Laurasiatheria |
| Order: | †Creodonta |
| Family: | †Hyaenodontidae |
| Subfamily: | †Hyainailourinae |
| Genus: | †Megistotherium Savage, 1973[1] |
| Species: | †M. osteothlastes |
| Synonyms | |
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Megistotherium (from Greek, megistos "greatest" + therion "beast" and osteon 'bone' + thlaston 'crushed, bruised' with -es being an agent noun: 'bone-crusher') is an extinct genus of creodonts, the only known species of which is Megistotherium osteothlastes.[2]. It is most likely a junior synonym of Hyainailouros sulzeri
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[edit] Description
Megistotherium osteothlastes was an enormous hyaenodontid creodont that lived during the early Miocene Epoch some 23 million years ago. It has been found in the Ngorora Formation and Muruyur Formation Kenya, Egypt[3], Namibia, Uganda[4] and Libya. Named by Robert Savage in 1973,[2] it is one of the largest terrestrial carnivorous mammals known to have existed. It was about 1.5 meters high at the shoulders and 3.5 meters in head and body length, with a 1 meter long tail and a 65 cm long skull.[5] Its body mass has been estimated at 500 kg[6] or 880 kg.[6]
This can be compared to the other large carnivorous mammals such as: Arctodus, modern polar bears, and Amphicyon ingens. The skull was twice as long as that of a Bengal tiger.
The carnassial teeth of Megistotherium (like those of other creodonts) were the upper first molars, and overlapped with their lower molar counterparts like scissors to form a formidable and powerful shearing action. 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 large fauna, which provided Megistotherium and other predators with an ample supply of prey. Large hyaenodontids like this one could have originally evolved as specialized predators or scavengers of large African herbivores.[7] Mastodon bones have been found with its fossils, indicating that Megistotherium may have hunted them for food.
[edit] Taxonomy
The order Creodonta comprised 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 occurred at that time. Hyainailouros sulzeri is very closely related to Megistotherium, extremely similar in size, structure and ratios - with a long tail, short limbs and robust body[8]. Morales & Pickford (2005)[9], Morlo, Miller & El-Barkooky (2007)[10] and Morales, Pickford & Salesa (2008)[11] suggested that Megistotherium is actually a junior synonym of Hyainailouros sulzeri, which is known by an almost complete skeleton[12], among other remains, and has been found in Europe, Asia and Namibia[13], and therefore comes from the same localities.
[edit] Notes
- ^ R. Savage, Megistotherium, gigantic hyaenodont from the Miocene of Gebel Zelten, Libya, Bull. Br. Mus. Nat. Hist. Geol. 22 (1973) 485–511.
- ^ a b "Megistotherium". Paleobiology Database. http://paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=40924&is_real_user=1. Retrieved January, 2010.
- ^ Morlo, M., Miller, E.R., and El-Barkooky, A.N. 2007. Creodonta and Carnivora from Wadi Moghra, Egypt. Journal of Vertebrate Paleontology 27: 145–159. doi:10.1671/0272-4634(2007)27[145:CACFWM]2.0.CO;2
- ^ MORALES, J. and M. PICKFORD. (2008). "Creodonts and carnivores from the Middle Miocene Muruyur Formation at Kipsaraman and Cheparawa, Baringo District, Kenya." Comptes Rendus Palevol 7 (8): 487-497
- ^ http://www.askabiologist.org.uk/answers/viewtopic.php?pid=863#p863
- ^ a b Sorkin, B. (2008-04-10). "A biomechanical constraint on body mass in terrestrial mammalian predators". Lethaia 41 (4): 333–347. doi:10.1111/j.1502-3931.2007.00091.x. http://onlinelibrary.wiley.com/resolve/doi?DOI=10.1111/j.1502-3931.2007.00091.x. Retrieved 2011-08-02.
- ^ Rasmussen, D. Tab; Tilden, Christopher D.; Simons, Elwyn L. (May, 1989). "New specimens of the giant creodont Megistotherium (Hyaenodontidae) from Moghara, Egypt". Journal of Mammalogy (American Society of Mammalogists) 70 (2): 442–447. http://www.jstor.org/pss/1381539.
- ^ Ginsburg, L. 1980. Hyainailouros sulzeri, mammifère créodonte du Miocène d’Europe. Ann. Paléont., 66, 19-73
- ^ Morales, J. and Pickford, M. 2005. Carnivores from the Middle Miocene Ngorora Formation (13-12 Ma) Kenya. Estudios Geol., 61, 271-284 http://digital.csic.es/bitstream/10261/2322/1/ngorora.pdf
- ^ Morlo, M., Miller, E.R., and El-Barkooky, A.N. 2007. Creodonta and Carnivora from Wadi Moghra, Egypt. Journal of Vertebrate Paleontology 27: 145–159.
- ^ MORALES J., PICKFORD M. & SALESA M. J. 2008. — Creodonta and Carnivora from the early Miocene of the northern Sperrgebiet, Namibia. Memoir of the Geological Survey of Namibia 20: 291-310
- ^ http://www.askabiologist.org.uk/answers/viewtopic.php?pid=863#p863
- ^ J. Morales, M. Pickford, S. Fraile, M.J. Salesa, D. Soria, Creodonta and Carnivora from Arrisdrift, early Middle Miocene of southern Namibia, Mem. Geol. Surv. Namibia 19 (2003) 177–194.
[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 0124404049.
