Tarbosaurus ( ; meaning "alarming lizard") is a genus of large tyrannosaurid dinosaur that lived in Asia during the Maastrichtian age of the Late Cretaceous period. It contains the type and single species Tarbosaurus bataar, which is known from the Nemegt Formation of Mongolia, with more fragmentary remains found further afield in the Subashi Formation of China. Tarbosaurus is represented by dozens of fossil specimens, including several complete skulls and skeletons. These remains have allowed studies focusing on its phylogeny, skull mechanics, and brain structure. Further fossil remains have been reported from other geologic formations of Asia, however, these remains are fragmentary and cannot be confidently assigned to Tarbosaurus or the type species.
Like most known tyrannosaurids, Tarbosaurus was a large bipedal predator, with the type specimen measuring approximately long, tall at the hips, and weighing up to . 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.
Although many species have been named, most modern paleontologists recognize only one species, T. bataar. Some experts see this species as an Asian representative of the North American genus Tyrannosaurus, which would make the genus Tarbosaurus redundant. Tarbosaurus and Tyrannosaurus, if not synonymous, are considered to be very closely related genera. 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.
Tarbosaurus lived in a humid floodplain dominated by deserts, forests, and plains, and criss-crossed by river channels. It was an apex predator in this environment, preying on other large dinosaurs including ankylosaurids, such as Tarchia and Saichania, hadrosaurids, such as Saurolophus and Barsboldia, and sauropods, such as Nemegtosaurus and Opisthocoelicaudia.
Discovery and naming
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. In 1955, Evgeny Maleev, a Soviet paleontologist, made this specimen the holotype (PIN 551–1) of a new species, which he called Tyrannosaurus bataar. The specific name is a misspelling of the Mongolian word баатар/baatar, meaning "hero". In the same year, Maleev also described and named three new theropod skulls, each associated with skeletal remains discovered by the same expedition in 1948 and 1949. The first of these, PIN 551–2, was named Tarbosaurus efremovi, a new generic name composed of the Ancient Greek words τάρβος (), meaning "terror", "alarm", "awe", or "reverence", and (), meaning "lizard", and the species was named after Ivan Yefremov, a Russian paleontologist and science fiction author. The other two, PIN 553-1 and PIN 552–2, were also named as new species and assigned to the North American genus Gorgosaurus as G. lancinator and G. novojilovi, respectively. All three of these latter specimens are smaller than the first.
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. He created a new combination, Tarbosaurus bataar, to include all the specimens described in 1955 and newer material. Later authors, including Maleev himself, agreed with Rozhdestvensky's analysis, although some used the name Tarbosaurus efremovi instead of T. bataar.
American paleontologist Ken Carpenter re-examined the material in 1992. He concluded that it belonged to the genus Tyrannosaurus, as originally published by Maleev, and lumped all the specimens into the species Tyrannosaurus bataar (except the remains that Maleev had named Gorgosaurus novojilovi). Carpenter thought this specimen represented a separate, smaller genus of tyrannosaurid, which he called Maleevosaurus novojilovi. George Olshevsky, Tracy Ford and Seiji Yamamoto 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. A 1999 study subsequently reclassified Maleevosaurus as a juvenile Tarbosaurus. Most research published since 1999 recognizes only a single species, which is either called Tarbosaurus bataar or Tyrannosaurus bataar, although some scholars suspect that there could be a second species.Raun G.S., Sharpe H.S., Powers M.J. & Currie P.J. (2025). "Who was the ruler of Maastrichtian Mongolia? Taxonomic revision of Tarbosaurus provides insight into tyrannosaurid diversity of central Asia". Canadian Society of Vertebrate Palaeontology Annual Meeting Abstracts 2025: p. 37. DOI: 10.18435/vamp29409
After the original Soviet-Mongolian expeditions in the 1940s, Polish-Mongolian joint expeditions to the Gobi Desert began in 1963 and continued until 1971, recovering many new fossils, including new specimens of Tarbosaurus from the Nemegt Formation. Expeditions involving Japanese and Mongolian scientists between 1993 and 1998, as well as private expeditions hosted by Canadian paleontologist Phil Currie around the turn of the 21st century, discovered and collected even more Tarbosaurus material. More than 30 specimens are known, including more than 15 skulls and several complete postcranial skeletons.
Synonyms
Chinese paleontologists discovered a partial skull and skeleton of a small theropod (IVPP V4878) in the Xinjiang Autonomous Region of China in the mid-1960s. In 1977, Dong Zhiming described this specimen, which was recovered from the Subashi Formation in Shanshan County, as a new genus and species, Shanshanosaurus huoyanshanensis. Gregory S. Paul recognized Shanshanosaurus as a tyrannosaurid in 1988, referring it to the dubious genus Aublysodon. Dong and Currie later re-examined the specimen and deemed it to be a juvenile of a larger species of tyrannosaurine. These authors refrained from assigning it to any particular genus, but suggested Tarbosaurus as a possibility. Subsequent authors have provisionally accepted S. houyanshanensis as a synonym of Tarbosaurus bataar.
Riabinin (1930b) described several fragments from the Yuliangze Formation of Heilongjiang, China as Albertosaurus periculosus.Riabinin, A. N. (1930). On the age and fauna of the dinosaur beds on the Amur River. Memoirs de la Société Russe de Mineralogie, 41-51. In the first edition of The Dinosauria, Molnar et al. (1990) listed A. periculosus as a provisional synonym of Tarbosaurus bataar, as followed by Holtz (2004) in the second edition. Olshevsky, Ford, and Yamamoto (1995) tentatively referred A. periculosus to Tarbosaurus, listing it as Tarbosaurus? periculosus. Alifanov and Bolotsky (2002) referred material from the neighboring Urduchukan Formation of Amur, Russia, to this taxon, but Bolotsky (2015) later regarded A. periculosus as a nomen dubium.Alifanov, V. R., Bolotsky, Y. L., & Kirillova, G. L. (2002). New data about the assemblages of the Upper Cretaceous carnivorous dinosaurs (Theropoda) from the Amur Region. Cretaceous continental margin of East Asia: stratigraphy, sedimentation, and tectonics, 25, 26.Bolotsky, I. Y. (2015). AN Riabinin and the first finds of tyrannosaurids (Dinosauria: Tyrannosauridae) in Asia. One Hundred Years of the Study of Dinosaurs in the Amur Region: Scientific Session Dedicated to the Outstanding Paleontologist and Geologist AN Riabinin: Collection of reports, December 18, 37-43.
Zhai et al. (1978) listed material from the Subashi Formation as Tyrannosaurus turpanensis.Zhai, R. J., Zheng, J. J., & Tong, Y. S. (1978). Stratigraphy of the mammal− bearing Tertiary of the Turfan Basin, Sinkiang. Memoirs of the Institute of Ver− tebrate Paleontology and Paleoantropology, 13, 68-81. Since the specific name "turpanensis" was published in a faunal list only and lacks a description, it is a nomen nudum according to ICZN Article 13.1. Olshevsky (1991) listed T. "turpanensis" under the combination Tarbosaurus "turpanensis." Several fragments from the Subashi Formation described by Dong (1977) as Tarbosaurus sp. may represent this taxon. As with Albertosaurus periculosus, Molnar et al. (1990) listed T. "turpanensis" as a provisional synonym of Tarbosaurus bataar without comment, as did Holtz (2004).
Dong (1979) described five teeth (IVPP V4733) discovered in the Quipa Formation of Henan, China as a new species, Tyrannosaurus luanchuanensis. Olshevsky (1991) listed it as Tarbosaurus luanchuanensis, and later in 1995, with Ford and Yamamoto, as Jenghizkhan luanchuanensis. Holtz (2004) listed it as a provisional synonym of Tarbosaurus bataar.
Along with Albertosaurus periculosus, Tyrannosaurus luanchuanensis, and Tyrannosaurus "turpanensis," Chingkankousaurus fragilis was considered a provisional junior synonym of Tarbosaurus bataar by Holtz (2004), but it has since been assessed as dubious by Brusatte et al. (2013).Brusatte, Hone and Xu, 2013. Phylogenetic revision of Chingkankousaurus fragilis, a forgotten tyrannosauroid from the Late Cretaceous of China. in Parrish, Molnar, Currie and Koppelhus (eds.). Tyrannosaurid Paleobiology. Indiana University Press. 1–13.
Named in 1976 by Sergei Kurzanov, Alioramus is another genus of tyrannosaurid from slightly older sediments in Mongolia. Several analyses have concluded Alioramus was quite closely related to Tarbosaurus. It was described as an adult, but its long, low skull is characteristic of a juvenile tyrannosaurid. 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.
Additional specimens
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. He tentatively referred these to Tarbosaurus sp. given some similarities in tooth morphology as well as the general geographic proximity to the Nemegt Formation. Translated paper In 1993 Tomasz Jerzykiewiczz examined the general outcrops from the Bayan Mandahu Formation of China. In this paper, he reported isolated tyrannosaurid premaxillary and maxillary teeth, which he assigned to Tarbosaurus without anatomical comparisons. Lev A. Nessov in 1995 reported a partial femur from the Bostobe Formation of Kazakhstan and referred it as Tarbosaurus sp. without any diagnosis. Translated paper
In 2004, David B. Weishampel and team listed a dubious Tarbosaurus? sp. as a component of the known dinosaur taxa of the Campanian-aged Djadokhta Formation without further ado. Despite this referral, scattered, and very sparse tyrannosaurid remains are occasionally found in the strata of the Djadokhta Formation of Mongolia and none of these remains have ever been diagnostically assigned to Tarbosaurus or even T. bataar. 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.
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. The specimen was found preserving a partial skeleton with a fairly complete skull. In 2011 this juvenile was formally described and referred to Tarbosaurus bataar, cataloged as MPC-D 107/7 within the collections of the Mongolian Paleontological Center.
Poached specimens