Tarbosaurus

Chapter • Meet the dinosaur

Overview

Tarbosaurus bataar was the largest carnivorous dinosaur of Asia and the closest known relative of Tyrannosaurus rex. It reached about 10–12 metres in length and weighed an estimated 4–5 tonnes. The body was held horizontally over two powerful hind limbs, balanced by a long, muscular tail that never dragged on the ground. The skull was up to 1.3 metres long, but slightly narrower and lower than that of T. rex, packed with deep jaw muscles and up to 60 thick, banana-shaped teeth. The forelimbs were extremely short and bore only two fingers – proportionally the shortest arms of any large tyrannosaurid. Skin impressions from close relatives show small pebbly scales; fine filament-like feathers may have persisted on parts of the body, especially in juveniles, but there is no direct evidence of feathers in Tarbosaurus itself. CT scans of the braincase reveal large olfactory regions and therefore an excellent sense of smell, while the eye sockets faced more sideways than in T. rex, so the fields of view overlapped less and depth perception was probably poorer. The lower jaw carried a distinctive locking ridge that slid in a groove, which may have stiffened the bite while the animal tore at large carcasses. Bite force was enormous but is calculated to have been somewhat lower than in its American cousin. Young Tarbosaurus were slender and long-legged with thinner teeth, suggesting that juveniles and adults hunted different prey and did not compete directly. Its food was the large herbivores of the Nemegt Formation: the hadrosaur Saurolophus angustirostris, the bizarre giant therizinosaur Therizinosaurus, sauropods such as Nemegtosaurus and Opisthocoelicaudia, and the armoured Saichania. Bite marks on hadrosaur bones show that Tarbosaurus both hunted and scavenged – like most big predators it was an opportunist. Tooth wear and jaw mechanics point to a puncture-and-pull feeding style, in which the teeth were driven deep into flesh and then pulled backwards. The first fossils were collected by a Soviet–Mongolian expedition in the Nemegt Basin in 1946, and the species was described in 1955 by the Russian palaeontologist Evgeny Maleev, originally as Tyrannosaurus bataar. More than 30 individuals have since been found, from small juveniles to full-grown giants, making Tarbosaurus one of the best-known large predatory dinosaurs anywhere. The genus has also made headlines for less pleasant reasons: a smuggled skeleton was auctioned in New York in 2012 and returned to Mongolia in 2013 after a widely reported court case.

Chapter • Where it lived

Habitat

Tarbosaurus lived in the Late Cretaceous, during the Maastrichtian stage about 70 million years ago. Its fossils come almost entirely from the Nemegt Formation in the Gobi Desert of southern Mongolia, from classic sites such as Nemegt, Altan Uul, Tsagan Khushu and Bugin Tsav; related material has also been reported from China. At the time the region was not a desert but a humid lowland of braided rivers, floodplains, lakes and swampy woodland – an environment rich in hadrosaurs, sauropods, therizinosaurs and turtles, and thus plenty of prey for a four-tonne predator.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy