Tarbosaurus (/ˌtɑːrbəˈsɔːrəs/ TAR-bə-SOR-əs; meaning "alarming lizard") is a genus of large tyrannosaurid dinosaur that lived in Asia during the Late Cretaceous epoch, about 70 million years ago (Maastrichtian age).

It had a unique locking mechanism in its jaw, equipped with about sixty large teeth, and the smallest arms relative to body size of all tyrannosaurids, renowned for their disproportionately tiny, two-fingered hands.

Alioramus, also from Mongolia, has previously been thought by some authorities to be the closest relative of Tarbosaurus, though this has since been disproven with the discovery of Qianzhousaurus and the description of the tyrannosaurine tribe Alioramini.

In this environment, it was an apex predator preying on other large dinosaurs, like ankylosaurids, such as Tarchia and Saichania, hadrosaurids, such as Saurolophus and Barsboldia, and sauropods, such as Nemegtosaurus and Opisthocoelicaudia.

In 1946, a joint Soviet-Mongolian expedition to the Gobi Desert in the Ömnögovi Province turned up a large theropod skull and some vertebrae from the Nemegt Formation.

[4] A 1965 paper by A. K. Rozhdestvensky recognized all of Maleev's specimens as different growth stages of the same species, which he believed to be distinct from the North American Tyrannosaurus.

[8] George Olshevsky created the new generic name Jenghizkhan (after Genghis Khan) for Tyrannosaurus bataar in 1995, while also recognizing Tarbosaurus efremovi and Maleevosaurus novojilovi, for a total of three distinct, contemporaneous genera from the Nemegt Formation.

This led Currie to speculate that Alioramus might represent a juvenile Tarbosaurus, but he noted that the much higher tooth count and row of crests on top of the snout suggested otherwise.

[23] In 1979 Dong Zhiming described several dinosaur remains from the strata of South China, reporting teeth, a dorsal vertebra, and several fragmentary foot bones of a tyrannosaurid.

[28][25][29][30] In addition, the extreme conditions of the Djadokhta Formation suggest that the remains of tyrannosaurids and other large-bodied dinosaurs from this unit represent passing by taxa foreign to the region.

[31] During a large fossil prospection led by the Hayashibara Museum of Natural Sciences-Mongolian Paleontological Center Joint Expedition, a juvenile tyrannosaurid was discovered in 2006 from the highly fossiliferous Bügiin Tsav locality where adult specimens of Tarbosaurus have been recovered.

[33] A $1 million smuggling deal was uncovered when suspicions were raised about a catalog put out by Heritage Auctions for an event in New York City on May 20, 2012.

[34] During the court case (United States v. One Tyrannosaurus Bataar Skeleton), Eric Prokopi, the smuggler, pleaded guilty to illegal smuggling and the dinosaur was returned to Mongolia in 2013, where it is temporarily displayed on Sukhbaatar Square, the center of the city of Ulaanbaatar.

These impressions show non-overlapping scales with an average diameter of 2.4 millimeters (0.094 in) and pertain to the thoracic region of the individual, although the exact position can no longer be assessed due to the destruction of the skeleton.

[38] In 1997, Ken Carpenter reported a damaged Tarbosaurus skull with impressions of a dewlap or throat pouch beneath the lower jaws, based on a personal communication from Konstantin Mikhailov.

The unexpanded rear of the skull meant that Tarbosaurus‘s eyes did not face directly forwards, suggesting that it lacked the binocular vision of Tyrannosaurus.

If proven, this relationship would argue against Tarbosaurus being a synonym of Tyrannosaurus and would suggest that separate tyrannosaurine lineages evolved in Asia and North America.

It was also discovered that Lythronax is a sister taxon to a clade consisting of Campanian genus Zhuchengtyrannus, and the Maastrichtian genera Tyrannosaurus and Tarbosaurus.

[51] Qianzhousaurus sinensis Alioramus remotus Alioramus altai Teratophoneus curriei Dynamoterror dynastes Lythronax argestes Nanuqsaurus hoglundi Thanatotheristes degrootorum Daspletosaurus torosus Daspletosaurus horneri Zhuchengtyrannus magnus Tarbosaurus bataar Tyrannosaurus rex Most specimens of Tarbosaurus represent adult or subadult individuals, while juveniles remain very rare.

Nevertheless, the 2006 discovery of a juvenile individual (MPC-D 107/7) with a complete, 290-millimeter (0.95 ft) long skull was reported and described in 2011, providing information on the life history of this dinosaur.

[57] However, this is contradicted by numerous lines of evidence indicating Tarbosaurus was actively preying on hadrosaurs, titanosaur sauropods, and other large bodied herbivores in its ecosystem.

[2] Some scientists have hypothesized that the more rigid skull of Tarbosaurus was an adaptation to hunting the massive titanosaurid sauropods found in the Nemegt Formation, which did not exist in most of North America during the Late Cretaceous.

[2] In 2001, Bruce Rothschild and others published a study examining evidence for stress fractures and tendon avulsions in theropod dinosaurs and the implications for their behavior.

[63] David W. E. Hone and Mahito Watabe in 2011 reported the left humerus of a nearly complete Saurolophus skeleton (MPC-D 100/764) from the Bügiin Tsav locality of the Nemegt Formation, which was heavily damaged from bite marks attributed to Tarbosaurus.

As suggested by the lack of damage to the rest of the skeleton (such as large wounds in skeletal remains indicative of predation), this tyrannosaurid was likely scavenging an already dead Saurolophus.

[65] A 2020 study involving stable isotopes found that Tarbosaurus primarily hunted large dinosaurs in its environment, most notably titanosaurs and hadrosaurs.

This geologic formation has never been dated radiometrically, but the fauna present in the fossil record indicate it was probably deposited during the early Maastrichtian stage at the near end of the Late Cretaceous,[67] about 70 million years ago.

Sediments also indicate that there existed a rich habitat, offering diverse food in abundant amounts that could sustain massive Cretaceous dinosaurs.

[71] Mammal fossils are exceedingly rare in the Nemegt Formation, but many birds have been found, including the enantiornithine Gurilynia and the hesperornithiform Judinornis, as well as Teviornis, an early representative of the still-existing Anseriformes.

However, as in other large tyrannosaurids, as well as modern Komodo dragons, juveniles and subadult Tarbosaurus would have filled niches between the massive adults and these smaller theropods.