Megistotherium

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 hyaenodontid, the only known species of which is Megistotherium osteothlastes.[2] It is possibly a junior synonym of Hyainailouros sulzeri (see below).

Megistotherium
Temporal range: early Miocene 23.03–11.61 Ma
Megistotherium osteothlastes
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: †Hyaenodonta
Family: †Hyaenodontidae
Subfamily: †Hyainailourinae
Genus: †Megistotherium
Savage, 1973[1]
Species:
†M. osteothlastes
Binomial name
†Megistotherium osteothlastes
Savage, 1973

Description

Megistotherium osteothlastes was a large hyaenodontid that lived during the early Miocene epoch some 23 million years ago. Its remains have been found in the Ngorora and Muruyur Formations of Kenya, Egypt,[3] Namibia, Uganda[4] and Libya. Named by Robert Savage in 1973,[2] Megistotherium is one of the largest hyaenodontids known. Like the other hyaenodontids, it had an enormous skull relative to its body; up to 66 cm (2 ft 2 in) in length[2] and a body mass estimated at 500 kg (1,100 lb).[5]

The carnassial teeth of Megistotherium (like those of other hyaenodontids) 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.[6] Gomphothere bones have been found with its fossils, indicating that Megistotherium may have hunted them for food.

Taxonomy

The clade Hyaenodontidae comprised a diverse group of creodont predators that were most successful during the Eocene before being possibly ecologically displaced by the order Carnivora during the late Oligocene. Megistotherium emerged in the Miocene towards the end of the hyaenodontids' 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.[7] Other authorities[8][3][4] have suggested that Megistotherium is actually a junior synonym of Hyainailouros sulzeri, which is known by an almost complete skeleton, among other remains, and has been found in Europe, Asia and Namibia,[9] and therefore comes from the same localities.

Notes
  1. F. Solé, J. Lhuillier, M. Adaci, M. Bensalah, M. Mahboubi and R. Tabuce. 2014. The hyaenodontidans from the Gour Lazib area (?Early Eocene, Algeria): implications concerning the systematics and the origin of the Hyainailourinae and Teratodontinae. Journal of Systematic Palaeontology 12(3):303-322
  2. Savage, R. J. G. (1973). "Megistotherium, gigantic hyaenodont from Miocene of Gebel Zelten, Libya". Bulletin of the British Museum (Natural History), Geology. 22 (7): 483–511.
  3. 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
  4. 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
  5. 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.
  6. 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. 70 (2): 442–447. doi:10.2307/1381539. JSTOR 1381539.
  7. Ginsburg, L. 1980. Hyainailouros sulzeri, mammifère créodonte du Miocène d’Europe. Ann. Paléont., 66, 19-73
  8. Morales, J. and Pickford, M. 2005. Carnivores from the Middle Miocene Ngorora Formation (13-12 Ma) Kenya. Estudios Geol., 61, 271-284
  9. 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.

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 0-12-440404-9.
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