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'''Tarbosaurus''' (meaning 'Alarming Reptile') is a genus of tyrannosaurid theropod dinosaur that flourished during the early Maastrichtian of the Late Cretaceous Period. Fossils have been recovered in Mongolia with more fragmentary remains found further afield in parts of China. Two species, ''T. efremovi'' and the larger ''T. bataar'', were initially recognized from the Mongolian finds though most now consider them different growth stages of one species. However, one authority has split the best known species ''T. bataar'', into its own genus.
''Tarbosaurus'' has held an uncertain taxonomic position within the tyrannosaur family; it is closely related to the genus ''Tyrannosaurus'', with some authorities considering it a species of the latter genus. Another study re-examining data determined it was more closely related to ''Alioramus''.
Like most known tyrannosaurids, it was a multi-ton bipedal predator equipped with dozens of large, sharp teeth. ''Tarbosaurus'' had the smallest forelimbs of all tyrannosaurids, already renowned for their disproportionately tiny arms. As an apex predator, ''Tarbosaurus'' was at the top of the food chain, probably preying on large dinosaurs like the hadrosaur ''Saurolophus''.

Contents

Classification and systematics

Issues with classification

Discovery and naming

Size

Paleobiology

Popular culture

Gallery

References

External links

Classification and systematics

''Tarbosaurus'' belongs in the subfamily Tyrannosaurinae within the family Tyrannosauridae, along with the earlier ''Daspletosaurus'', the more recent ''Tyrannosaurus'' and possibly ''Alioramus''. Animals in this subfamily are more closely related to ''Tyrannosaurus'' than to ''Albertosaurus'' and are known for their robust build with proportionally larger skulls and longer femurs than in the other subfamily, the Albertosaurinae.
Although many specimens of this genus have been found, little definite data was confirmed on the dinosaur as of 1986, though it was presumed to share many characteristics with other tyrannosaurids. The close similarities have prompted some scientists to suggest a possible link between the North American and Eurasian continents at that time, perhaps in the form of a land bridge.

Issues with classification

''Tarbosaurus'' skull

''Tarbosaurus'' skeleton in University Geology and Palaentology Museum, Münster, Germany.

Smaller specimens, retrieved on the same expedition, were described as ''Tarbosaurus efremovi''. It is unclear if they were merely subadults of ''T. bataar'', as thought by Rozhdestvensky, or a different species. The latest consensus is that ''Maleevosaurus novojilovi'', ''Gorgosaurus lancinator'', and ''T. efremovi'' are regarded as young specimens of ''T. bataar''. Additionally, ''Shanshanosaurus huoyanshanensis'',Dong, Z. (1977). On the dinosaurian remains from Turpan, Xinjiang. ''Vertebrata PalAsiatica'' 15(1):59-66. a partial skeleton and skull of a juvenile tyrannosaurid from the Nemegt Formation, is likely a young ''T. bataar''.Currie, P.J. (2003). Allometric growth in tyrannosaurids (Dinosauria: Theropoda) from the Upper Cretaceous of North America and Asia. ''Canadian Journal of Earth Sciences'' 40:651-655.Holtz, Jr., T.R. (2004). Tyrannosauroidea. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria (second edition)''. University of California Press:Berkeley, 111-136.
Opinion has been divided on this too, however, with George Olshevsky (1995) analysing ''Tarbosaurus efremovi'' as a species and genus distinct from ''T. bataar'', leaving it requiring a new genus. Olshevsky coined the name ''Jenghizkhan bataar'', named for Genghis Khan. The second part of the name is an accidental misspelling of the Mongolian word baatar (hero).
Others, such as Carpenter, place it in the ''Tyrannosaurus'' genus (the resulting designation would then be ''Tyrannosaurus bataar''), as the skull seems to have many similarities with its North American cousin, ''Tyrannosaurus rex''. Hurum and Sabath in 2003, however, demonstrated that ''Tarbosaurus'' is a relative of ''Alioramus'', and not a species of ''Tyrannosaurus''. This was based on supporting evidence for the hypothesis that tyrannosaurids originated in Asia, and then migrated to North America.Hurum JH & Sabath K. (2003). Giant theropod dinosaurs from Asia and North America: Skulls of ''Tarbosaurus bataar'' and ''Tyrannosaurus'' rex compared. ''Acta Palaeontologica Polonica'' '48' (2), 161-190 Other authorities have supported this view.Xu X., Norell, M.A., Kuang X., Wang. X., Zhao Q., and Jia C. (2004). Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids. ''Nature'' '431':680-684.

Discovery and naming

''Tarbosaurus'' remains have been found in Mongolia, first being described by Evgeny Maleev, in 1955, from fossils recovered in a Soviet Mongolian expedition in 1948. The translation of the name is, aptly, 'Terror Lizard' (from the Greek '''tarbos/ταρβος''' meaning 'fright', 'alarm', 'terror' (interestingly it can also mean 'awe' or 'reverence'^[1]) and '''saurus/σαυρος''' meaning 'lizard') More recently, some teeth and parts of a large pelvis, from a possible tarbosaur, have been recovered from the late Cretaceous Subashi Formation in the Turpan Basin in Xinjiang province of western China.^[2] Several tarbosaur teeth have also been recovered, from the Late Cretaceous Nanxiong Formation in Guandong Province in southern China.
''Tarbosaurus'' species

★ ''T. bataar''
Missassigned (Probable)

★ ''T. efremovi'' (actually young ''T. bataar'') (type)
★ ''T. novojilovi'' (actually young ''T. bataar'')
★ ''T. lanpingensis'' (actually young ''T. bataar'')
★ ''T. turpanensis'' (actually young ''T. bataar'')
★ ''T. luanchuanensis'' (actually a nomen dubium species of ''Tyrannosaurus'', perhaps a young ''T. bataar''
More remains from China, this time, ''Chingkankousaurus'', named by Chung Chien Young in 1958; was then considered a ''nomen dubium'' by Dong (1992); and then synonymized subjectively with ''Tarbosaurus'' by Holtz, Jr.

Size

''Tarbosaurus baatar'' with a human for scale.

As with most dinosaurs, ''Tarbosaurus'' size estimates have varied through recent years. It could have been 10 meters long, with a weight of 4 to 5 tons.

Paleobiology

''Tarbosaurus'' may have preyed upon large contemporary hadrosaurs, such as ''Saurolophus'' which has been found in several of the same formations.

Popular culture

★ A mounted cast of a ''Tarbosaurus'' skeleton can be seen in the Melbourne Museum in Carlton, Victoria. Another specimen is on display in the entrance foyer of the library at Macquarie University in Sydney.

★ A ''Tarbosaurus'' makes an appearance in the second episode of ''The Truth About Killer Dinosaurs'' (2005) and also appeared in the ''Walking with Dinosaurs'' Special ''The Giant Claw''.

Gallery

References

1. Greek-English Lexicon, Abridged Edition, Liddell & Scott, , , Oxford University Press, Oxford, UK, 1980, ISBN 0-19-910207-4
2. Dinosaurian Faunas of China, Dong Zhiming, , , China Ocean Press, Beijing, 1992, ISBN 3-540-52084-8


★ The Complete ''T. Rex.''/How Stunning New Discoveries Are Changing Our Understanding of the World's Most Famous Dinosaur, Horner, John R.; Lessem, Don, , , Simon and Schuster, 1993, ISBN 0-671-74185-3

★ Carr, TD (1999). Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19: 497-520

★ Online Abstract of preceding article

★ Holtz TR, Jr. (1994). The phylogenetic position of the Tyrannosauridae: implication for theropod systematics. Journal of Paleontology 68: 1100-1117.

External links

★ Currie, P. J., Hurum, J. H. and Sabath, K. 2003. Skull structure and evolution in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 48 (2), 227-234. http://www.app.pan.pl/acta48/app48-227.pdf

★ Hurum, J. H. and Sabath, K. 2003. Giant theropod dinosaurs from Asia and North America: Skulls of ''Tarbosaurus bataar'' and ''Tyrannosaurus rex'' compared. Acta Palaeontologica Polonica 48 (2), 161-190. http://www.app.pan.pl/acta48/app48-161.pdf

★ Review Of The Tyrannosauridae, George Olshevsky (1995)