''Tarbosaurus'' ( ; meaning "alarming lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

tyrannosaurid Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

that flourished in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

about 70

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

, at the end of the Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

, considered to contain a single known species, ''Tarbosaurus bataar''.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have been recovered from the

Nemegt Formation The Nemegt Formation (also known as Nemegtskaya Svita) is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilians, ...

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

, with more fragmentary remains found further afield in the

Subashi Formation The Subashi Formation () is a Late Cretaceous (Campanian to Maastrichtian)Xi et al., 2018 formation from the Xinjiang Autonomous Region of western China.China. Although many

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

have been named, modern paleontologists recognize only one, ''T. bataar'', as valid. Some experts see this species as an Asian representative of the North American genus ''

Tyrannosaurus ''Tyrannosaurus'' is a genus of large theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosaurus'' live ...

''; this would make the genus ''Tarbosaurus'' redundant. ''Tarbosaurus'' and ''Tyrannosaurus'', if not synonymous, are considered to be at least closely related genera. ''

Alioramus ''Alioramus'' (; meaning 'different branch') is a genus of tyrannosaurid theropod dinosaurs from the Late Cretaceous period of Asia. It currently contains two species. The type species, ''A. remotus'' is known from a partial skull and thre ...

'', 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 Alioramini. Like most known tyrannosaurids, ''Tarbosaurus'' was a large

biped Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

, measuring approximately in length, in hip height and weighing up to in body mass. It had a unique locking mechanism in its jaw, equipped with about sixty large teeth, and the smallest forelimbs relative to body size of all tyrannosaurids, renowned for their disproportionately tiny, two-fingered forelimbs. ''Tarbosaurus'' lived in a humid

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

criss-crossed by river channels. In this environment, it was an

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...

, probably preying on other large dinosaurs like the

hadrosaur Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which incl ...

'' Saurolophus'' or the sauropod ''

Nemegtosaurus ''Nemegtosaurus'' (meaning 'Reptile from the Nemegt') was a sauropod dinosaur from the Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. ...

''. ''Tarbosaurus'' is represented by dozens of

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

specimens, including several complete skulls and skeletons. These remains have allowed scientific studies focusing on its

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spe ...

, skull mechanics, and brain structure.

Discovery and naming

In 1946, a joint

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

-Mongolian expedition to the Gobi Desert in the Mongolian

Ömnögovi Province Ömnögovi ( mn, Өмнөговь ''Ömnögovǐ'', ''South Gobi'') is an aimag (province) of Mongolia, located in the south of the country, in the Gobi Desert. Ömnögovi is Mongolia's largest aimag. The capital is Dalanzadgad. The province is ...

turned up a large theropod skull and some

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e in the

. In 1955,

Evgeny Maleev Evgeny Aleksandrovich Maleev (, ; 25 February 1915 – 12 April 1966) was a Soviet and Russian paleontologist who did most of his research on reptiles and Asian fossils, such as the naming of the ankylosaur '' Talarurus'' and theropods ''Tarb ...

, a Soviet

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

, made this specimen the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

(

PIN A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch ...

551–1) of a new species, which he called ''Tyrannosaurus bataar''. The specific name is a misspelling of the Mongolian баатар/''baatar'' ("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 Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

''τάρβος'' (') ("terror", "alarm", "awe", or "reverence") and (') ("lizard"), and the species named after

Ivan Yefremov Ivan Antonovich (real patronymic Antipovich) Yefremov ( ru , Ива́н Анто́нович (Анти́пович) Ефре́мов; April 23, 1908 – October 5, 1972; last name sometimes transliterated as Efremov) was a Soviet paleonto ...

, a Russian paleontologist and

science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel uni ...

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 ''Gorgosaurus'' ( ; ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (Campanian), between about 76.6 and 75.1 million years ago. Fossil remains have been found in the Ca ...

'' (''G. lancinator'' and ''G. novojilovi'', respectively). All three of these latter specimens are smaller than the first. Tarbosaurus Warsaw3

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 ''

''. He created a new combination, ''Tarbosaurus bataar'', to include all the specimens described in 1955 as well as newer material. Later authors, including Maleev himself, agreed with Rozhdestvensky's analysis, although some used the name ''Tarbosaurus efremovi'' rather than ''T. bataar''. American paleontologist

Kenneth Carpenter Kenneth Carpenter (born September 21, 1949, in Tokyo, Japan) is a paleontologist. He is the former director of the USU Eastern Prehistoric Museum and author or co-author of books on dinosaurs and Mesozoic life. His main research interests ...

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 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''. All research published since 1999 recognizes only a single species, which is either called ''Tarbosaurus bataar'' or ''Tyrannosaurus bataar''. After the original Russian-Mongolian expeditions in the 1940s,

Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavic nation and ethnic group, w ...

-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 Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...

paleontologist

Phil Currie Philip John Currie (born March 13, 1949) is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton. In the ...

around the turn of the 21st century, discovered and collected further ''Tarbosaurus'' material. More than 30 specimens are known, including more than 15 skulls and several complete postcranial skeletons.

Poached specimens

''Tarbosaurus'' fossils are only found around the Gobi Desert of Mongolia and China, both of which ban their export, though some specimens have been looted by private collectors. 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. By Mongolian law, any specimen found in the Gobi Desert was to rest at an appropriate Mongolian institution and there was little reasonable doubt that the ''Tarbosaurus bataar'' advertised on the catalog was a stolen one. The president of Mongolia and many paleontologists raised objections to the sale which led to a last-minute investigation that confirmed that it was a specimen that can only be found in the Gobi Desert, rightfully belonging to Mongolia. During the court case ( United States v. One ''Tyrannosaurus Bataar'' Skeleton),

Eric Prokopi ''United States v. One Tyrannosaurus Bataar Skeleton'' (1:13−cv−00857) is a 2013 United States District Court for the Southern District of New York judgment regarding a requested order from the United States government to seize an imported ...

, 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. Prokopi had sold the dinosaur with a partner and fellow commercial hunter in England, Christopher Moore. The case led to the repatriation of dozens more Mongolian dinosaurs, including several skeletons of ''Tarbosaurus bataar''.

Synonyms

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...

paleontologists discovered a partial skull and skeleton of a small theropod ( IVPP V4878) in the

Xinjiang Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest ...

Autonomous Region of China in the mid-1960s. In 1977,

Dong Zhiming Dong Zhiming (Chinese: 董枝明, Pinyin: ''Dǒng Zhimíng''; born January 1937) is a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. He began working at th ...

described this specimen, which was recovered from the

Subashi Formation The Subashi Formation () is a Late Cretaceous (Campanian to Maastrichtian)Xi et al., 2018 formation from the Xinjiang Autonomous Region of western China.Shanshan County, as a new genus and species, ''Shanshanosaurus huoyanshanensis''.

Gregory Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dino ...

recognized ''Shanshanosaurus'' as a tyrannosaurid in 1988, referring it to the now-defunct genus ''

Aublysodon ''Aublysodon'' (“backwards-flowing tooth") is a genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago). The ...

''. 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. ''Albertosaurus periculosus'', ''Tyrannosaurus luanchuanensis'', ''Tyrannosaurus turpanensis'' and '' Chingkankousaurus fragilis'' were considered synonyms of ''Tarbosaurus'' in the second edition of the Dinosauria, but ''Chingkankousaurus'' has been assessed as dubious by Brusatte et al. (2013). Named in 1976 by Sergei Kurzanov, ''

'' 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.

Skin impressions and footprints

Skin impressions were recovered from a large skeleton at the Bugiin Tsav locality that was subsequently destroyed by poachers. These impressions show non-overlapping scales with an average diameter of and pertain to the thoracic region of the individual, although the exact position can not be assessed any longer due to the destruction of the skeleton.

and colleagues (2003) described two footprints from the Nemegt locality that probably pertain to ''Tarbosaurus''. These tracks represent natural casts, which means that only the sandy infill of the tracks and not the tracks themselves are preserved. The better-preserved track features skin impressions over large areas on and behind the toe impressions that are similar to those discovered in Bugiin Tsav; it also features vertical parallel slide marks that were left by scales when the foot was pushed into the ground. The track measures in length, thus representing a large individual. The second track, although even larger, was affected by

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

and does not show any detail. In 1997, Kenneth 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. Carpenter speculated that the pouch may have been used for display, possibly being brightly colored and inflatable like a frigatebird's. In a 2019 communication to Mickey Mortimer, Mikhailov confirmed that this specimen had not been collected due to its being on a heavy stone slab. He revealed that it had been discovered by Sergei Kurzanov and that it was Kurzanov who had originally interpreted the impressions as a throat structure. This specimen may be the same as one that was purportedly destroyed by poachers in 1992.

Description

Although slightly smaller than ''Tyrannosaurus'', ''Tarbosaurus'' was one of the largest tyrannosaurids, with the largest fully grown individual measuring approximately in length, in hip height and weighing up to in body mass (based on tibia and femur circumference and volumetric analysis). The largest known ''Tarbosaurus'' skull is more than long, larger than all other tyrannosaurids except ''Tyrannosaurus''.

Skull

The skull was tall, like that of ''Tyrannosaurus'', but not as wide, especially towards the rear. The unexpanded rear of the skull meant that ''Tarbosaurus'' eyes did not face directly forwards, suggesting that it lacked the

binocular vision In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an ...

of ''Tyrannosaurus''. Large

fenestra A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...

e (openings) in the skull reduced its weight. Between 58 and 64 teeth lined its jaws, slightly more than in ''Tyrannosaurus'' but fewer than in smaller tyrannosaurids like ''

'' and ''Alioramus''. Most of its teeth were oval in

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...

, although the teeth of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

at the tip of the upper jaw had a ''D''-shaped cross section. This

heterodonty In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology. In vertebrates, heterodont pertains to animals where teeth are differentiated into different forms. For example ...

is characteristic of the family. The longest teeth were in the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

(upper jaw bone), with

crowns A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...

up to 85 millimeters (3.3 in) long. In the

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, a ridge on the outer surface of the angular bone articulated with the rear of the

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

bone, creating a locking mechanism unique to ''Tarbosaurus'' and ''Alioramus''. Other tyrannosaurids lacked this ridge and had more flexibility in the lower jaw.

Postcranial skeleton

Tyrannosaurids varied little in body form, and ''Tarbosaurus'' was no exception. The head was supported by an ''S''-shaped neck, while the rest of the

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

, including the long tail, was held horizontally. ''Tarbosaurus'' had tiny forelimbs, proportionably to body size the smallest of all members of the family. The hands had two clawed digits each, with an additional unclawed third metacarpal found in some specimens, similar to closely related genera. Holtz has suggested that ''Tarbosaurus'' also has a theropod reduction of fingers IV-I "developed further" than in other tyrannosaurids,Carpenter K, Tanke D.H. & Skrepnick M.W. (2001), ''Mesozoic Vertebrate Life'' ( Indiana University Press, ), p. 71. as the second metacarpal in the ''Tarbosaurus'' specimens he studied is less than twice the length of the first metacarpal (other tyrannosaurids have a second metacarpal about twice the length of the first metacarpal). Also, the third metacarpal in ''Tarbosaurus'' is proportionally shorter than in other tyrannosaurids; in other tyrannosaurids (like ''

Albertosaurus ''Albertosaurus'' (; meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 71 million years ago. The type species, ''A. sarcophagus'', wa ...

'' and '' Daspletosaurus''), the third metacarpal is often longer than the first metacarpal, while in the ''Tarbosaurus'' specimens studied by Holtz, the third metacarpal is shorter than the first. In contrast to the forelimbs, the three-toed hindlimbs were long and thick, supporting the body in a bipedal posture. The long, heavy tail served as a

counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wea ...

to the head and torso and placed the

center of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force ma ...

over the hips.

Classification

''Tarbosaurus'' is classified as a

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

in the subfamily Tyrannosaurinae within the family

Tyrannosauridae Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

. Other members include ''Tyrannosaurus'' and the earlier '' Daspletosaurus'', both from North America, and possibly the Mongolian genus ''Alioramus''. Animals in this subfamily are more closely related to ''Tyrannosaurus'' than to ''

'' and are known for their robust build with proportionally larger skulls and longer

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

s than in the other subfamily, the Albertosaurinae. ''Tarbosaurus bataar'' was originally described as a species of ''Tyrannosaurus'', an arrangement that has been supported by some more recent studies. Others prefer to keep the genera separate, while still recognizing them as

sister taxa In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

. A 2003

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analysis based on skull features instead identified ''Alioramus'' as the closest known relative of ''Tarbosaurus'', as the two genera share skull characteristics that are related to stress distribution and that are not found in other tyrannosaurines. If proven, this relationship would argue against ''Tarbosaurus'' becoming a synonym for ''Tyrannosaurus'' and would suggest that separate tyrannosaurine lineages

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

in Asia and North America. The two known specimens of ''Alioramus'', which show juvenile characteristics, are not likely juvenile individuals of ''Tarbosaurus'' because of their much higher tooth count (76 to 78 teeth) and their unique row of bony bumps along the top of their snouts. The discovery of '' Lythronax argestes'', a much earlier tyrannosaurine further reveals the close relationship between ''Tyrannosaurus'' and ''Tarbosaurus'', and it was discovered that ''Lythronax'' is a sister taxon to a clade consisting of Campanian genus ''Zhuchengtyrannus'', and Maastrichtian genera ''Tyrannosaurus'' and ''Tarbosaurus''. Further studies of ''Lythronax'' also suggest that the Asian tyrannosauroids were part of one evolutionary radiation. Below is the cladogram of Tyrannosaurinae based on the

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

conducted by Voris and team in 2020.

Paleobiology

Ontogeny

Most specimens of ''Tarbosaurus'' represent adult or subadult individuals; juveniles remain very rare. Nevertheless, the 2006 discovery of a juvenile individual (MPC-D 107/7) including a complete, long skull was reported and described in 2011 and provides information on the life history of this dinosaur. This individual probably was aged 2 to 3 years at the time of death. Compared with adult skulls, the juvenile skull was weakly constructed and the teeth were thin, indicating different food preferences in juveniles and adults that reduced competition between different age groups. Examination of the sclerotic rings in this juvenile ''Tarbosaurus'' suggests they may also have been crepuscular or nocturnal hunters. Whether the adult ''Tarbosaurus'' were also nocturnal is currently unknown due to lack of fossil evidence.

Senses

A ''Tarbosaurus'' skull found in 1948 by Soviet and Mongolian scientists (PIN 553–1, originally called ''Gorgosaurus lancinator'') included the skull cavity that held the brain. Making a plaster

cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William ...

, called an ''

endocast An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible sp ...

'', of the inside of this cavity allowed Maleev to make preliminary observations about the shape of a ''Tarbosaurus'' brain. A newer

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from ...

rubber cast allowed a more detailed study of ''Tarbosaurus'' brain structure and function. The endocranial structure of ''Tarbosaurus'' was similar to that of ''Tyrannosaurus'', differing only in the positions of some cranial nerve roots, including the

trigeminal In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; ...

and

accessory nerve The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerv ...

s. Tyrannosaurid brains were more similar to those of

crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest livi ...

ns and other nonavian reptiles than to

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s. The total brain volume for a ''Tarbosaurus'' is estimated at only . The large size of the

olfactory bulb The olfactory bulb (Latin: ''bulbus olfactorius'') is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex ( ...

s, as well as the

terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output dev ...

and olfactory nerves, suggest that ''Tarbosaurus'' had a keen

sense of smell The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, ...

, as was also the case with ''Tyrannosaurus''. The vomeronasal bulb is large and differentiated from the olfactory bulb, which was initially suggested as being indicative of a well-developed Jacobsen's organ, which was used to detect

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

s. This may imply that ''Tarbosaurus'' had complex mating behavior. However, the identification of the vomeronasal bulb has been challenged by other researchers, since they are not present in any living archosaurs. The

auditory nerve The cochlear nerve (also auditory nerve or acoustic nerve) is one of two parts of the vestibulocochlear nerve, a cranial nerve present in amniotes, the other part being the vestibular nerve. The cochlear nerve carries auditory sensory information ...

was also large, suggesting good

hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is audit ...

, which may have been useful for auditory

communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...

and spatial awareness. The nerve had a well-developed

vestibular The Vestibular (from pt, vestíbulo, "entrance hall") is a competitive examination and is the primary and widespread entrance system used by Brazilian universities to select the students admitted. The Vestibular usually takes place from Nove ...

component as well, which implies a good sense of balance and coordination. In contrast, the nerves and brain structures associated with

eyesight Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflect ...

were smaller and undeveloped. The midbrain tectum, responsible for visual processing in reptiles, was very small in ''Tarbosaurus'', as were the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

and the oculomotor nerve, which controls eye movement. Unlike ''Tyrannosaurus'', which had forward-facing eyes that provided some degree of binocular vision, ''Tarbosaurus'' had a narrower skull more typical of other tyrannosaurids in which the eyes faced primarily sideways. All of this suggests that ''Tarbosaurus'' relied more on its senses of smell and hearing than on its eyesight. It has been suggested that the lack of binocular vision in Asian tyrannosaurs like ''Tarbosaurus'' might have been correlated with a greater amount of scavenging resources provided by sauropod carcasses, which might have afforded them a less active predatory lifestyle compared to the North American forms, and thus less predatory adaptations.

Skull mechanics

The skull of ''Tarbosaurus'' was completely described for the first time in 2003. Scientists noted key differences between ''Tarbosaurus'' and the North American tyrannosaurids. Many of these differences are related to the handling of stress by the skull bones during a bite. When the upper jaw bit down on an object, force was transmitted up through the maxilla, the primary tooth-bearing bone of the upper jaw, into surrounding skull bones. In North American tyrannosaurids, this force went from the maxilla into the fused nasal bones on top of the snout, which were firmly connected in the rear to the

lacrimal bone The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of ...

s by bony struts. These struts locked the two bones together, suggesting that force was then transmitted from the nasals to the lacrimals. ''Tarbosaurus'' lacked these bony struts, and the connection between the nasals and lacrimals was weak. Instead, a backwards projection of the maxilla was massively developed in ''Tarbosaurus'' and fit inside a sheath formed from the lacrimal. This projection was a thin, bony plate in North American tyrannosaurids. The large backwards projection suggests that force was transmitted more directly from the maxilla to the lacrimal in ''Tarbosaurus''. The lacrimal was also more firmly anchored to the

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music * The Front (band), an American rock band signed to Columbia Records and active in the 1980s and e ...

and

prefrontal bone The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha. The prefrontal is found in most modern a ...

s in ''Tarbosaurus''. The well-developed connections between the maxilla, lacrimal, frontal and prefrontal would have made its entire upper jaw more rigid. Another major difference between ''Tarbosaurus'' and its North American relatives was its more rigid mandible (lower jaw). While many theropods, including North American tyrannosaurids, had some degree of flexibility between the bones in the rear of the mandible and the dentary in the front, ''Tarbosaurus'' had a locking mechanism formed from a ridge on the surface of the angular, which articulated with a square process on the rear of the dentary. Some scientists have hypothesized that the more rigid skull of ''Tarbosaurus'' was an adaptation to hunting the massive

titanosaurid Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of '' Malawisaurus'' and '' Saltasaurus'' ...

sauropods found in the Nemegt Formation, which did not exist in most of North America during the Late Cretaceous. The differences in skull mechanics also affect tyrannosaurid phylogeny. ''Tarbosaurus''-like articulations between the skull bones are also seen in ''Alioramus'' from Mongolia, suggesting that it, and not ''Tyrannosaurus'', is the closest relative of ''Tarbosaurus''. Similarities between ''Tarbosaurus'' and ''Tyrannosaurus'' might, therefore, be related to their large size, independently developed through

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

Bite force and feeding

Saurolophus MPC-D 100 764 humerus injuries

In 2001, Bruce Rothschild and others published a study examining evidence for

stress fracture A stress fracture is a fatigue-induced bone fracture caused by repeated stress over time. Instead of resulting from a single severe impact, stress fractures are the result of accumulated injury from repeated submaximal loading, such as running or ...

s and tendon avulsions in

dinosaurs and the implications for their behavior. Since stress fractures are caused by repeated trauma rather than singular events they are more likely to be caused by regular behavior than other types of injuries. None of the eighteen ''Tarbosaurus'' foot bones examined in the study was found to have a stress fracture, but one of the ten examined hand bones was found to have one. Stress fractures in the hands have special behavioral significance compared to those found in the feet since stress fractures there can be obtained while running or during migration. Hand injuries, by contrast, are more likely to be obtained while in contact with struggling prey. The presence of stress fractures and tendon avulsions, in general, provide evidence for a "very active" predation-based diet rather than obligate scavenging.Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 331-336. As for its bite force, it was revealed in 2005 that ''Tarbosaurus'' had a bite force of around 8,000 to 10,000 pounds per force, meaning that it could possibly crush bone like its North American relative, ''Tyrannosaurus''. 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 Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

), this tyrannosaurid was likely

scavenging Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding ...

an already dead ''Saurolophus''. It is unlikely that a large-bodied predator such as ''Tarbosaurus'' would have left sparse feeding traces on a single humerus having an entire carcass to feed on. The humerus shows three distinctive feeding methods, interpreted as punctures, drag marks, and bite−and−drag marks. Hone and Watabe noted that bite marks were mostly located at the deltopectoral crest, suggesting that this ''Tarbosaurus'' was actively selecting which biting style employ to scavenge the bone. In 2012, bite marks on two fragmentary

gastralia Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In thes ...

of the holotype specimen of the large ornithomimosaur '' Deinocheirus mirificus'' were reported. The size and shape of the bite marks match the teeth of ''Tarbosaurus'', the largest known predator from the Nemegt Formation. Various types of feeding traces were identified; punctures, gouges, striae, fragmentary teeth, and combinations of the above marks. The bite marks probably represent feeding behavior instead of aggression between the species, and the fact that bite marks were not found elsewhere on the body indicates the predator focused on internal organs. ''Tarbosaurus'' bite marks have also been identified on hadrosaur and sauropod fossils, but theropod bite marks on bones of other theropods are very rare in the fossil record. A 2020 study involving stable isotopes found that ''Tarbosaurus'' primarily hunted large dinosaurs in its environment, most notably titanosaurs and hadrosaurs.

Paleoenvironment

Cretaceous-aged dinosaur fossil localities of Mongolia

The vast majority of known ''Tarbosaurus'' fossils were recovered from the

in the Gobi Desert of southern Mongolia. This

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

has never been dated radiometrically, but the

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is ''funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''Biota (ecology ...

present in the fossil record indicate it was probably deposited during the early

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

stage, at the near end of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

about 70 million years ago.Sulliban, R.M. (2006). "A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia)." Pp. 347-366 in Lucas, S.G. and Sullivan, R.M. (eds.), ''Late Cretaceous vertebrates from the Western Interior.'' New Mexico Museum of Natural History and Science Bulletin 3. The

Subashi Formation The Subashi Formation () is a Late Cretaceous (Campanian to Maastrichtian)Xi et al., 2018 formation from the Xinjiang Autonomous Region of western China.Barun Goyot The Barun Goyot Formation (also known as Baruungoyot Formation or West Goyot Formation) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Pro ...

and

Djadochta Formation The Djadochta Formation (sometimes Transcription (linguistics), transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Creta ...

s. However,

caliche Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions ...

deposits indicate at least periodic droughts. Sediment was deposited in the channels and floodplains of large rivers. The rock facies of this formation suggest the presence of mudflats, and shallow lakes. Sediments also indicate that there existed a rich habitat, offering diverse food in abundant amounts that could sustain massive Cretaceous dinosaurs.Novacek, M. (1996). Dinosaurs of the Flaming Cliffs. Bantam Doubleday Dell Publishing Group Inc. New York, New York. Fossils of an unidentified tyrannosaur from the older Djadochta Formation, which closely resemble those of ''Tarbosaurus'', may indicate that it also lived at an earlier time and in a more arid ecosystem than that of the Nemegt. TarbosaurusDB

Occasional

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

fossils are found, as well as a variety of other aquatic animals like fish and turtles. Crocodilians included several species of ''

Paralligator ''Paralligator'' is an extinct genus of neosuchian crocodylomorph that lived during the Late Cretaceous (Cenomanian-Maastrichtian) period in what is now the Bayan Shireh and Nemegt formations of Mongolia, approximately 96 million to 70 million ...

'', a genus with teeth adapted for crushing shells. Mammal fossils are exceedingly rare in the Nemegt Formation, but many birds have been found, including the enantiornithine ''

Gurilynia ''Gurilynia'' is a genus of enantiornithine birds.Kurochkin, E.N. (1999) "A new large enantiornithid from the Late Cretaceous of Mongolia." In I. Darevskii and A. Averianov (editors), "Materials on the History of Fauna of Eurasia. Zoological Ins ...

'' and the hesperornithiform ''

Judinornis ''Judinornis'' is a genus of prehistoric flightless birds from the late Cretaceous period. The single known species is ''Judinornis nogontsavensis''. Its fossils have been found in Nemegt Formation rocks of southern Mongolia, and though the age ...

'', as well as ''

Teviornis ''Teviornis'' is a genus of extinct birds. One species has been described, ''T. gobiensis''. It lived in the Maastrichtian stage at the end of the Late Cretaceous period, some 70 million years ago. It is known from fossils collected from the Nem ...

'', an early representative of the still-existing Anseriformes (waterfowl). Scientists have described many dinosaurs from the Nemegt Formation, including the

ankylosaurid Ankylosauridae () is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known Ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Pal ...

Saichania ''Saichania'' (Mongolian meaning "beautiful one") is a genus of herbivorous ankylosaurid dinosaur from the Late Cretaceous period of Mongolia and China. The first fossils of ''Saichania'' were found in the early 1970s in Mongolia. In 1977 the ...

'', and pachycephalosaur ''

Prenocephale ''Prenocephale'' (meaning "sloping head") is a genus of small pachycephalosaurid dinosaur from the Late Cretaceous Nemegt Formation of Mongolia. It was similar in many ways to its close relative, '' Homalocephale''. Description Adult ''Prenoce ...

''. By far the largest predator known from the formation, adult ''Tarbosaurus'' most likely preyed upon large hadrosaurs such as '' Saurolophus'' and '' Barsboldia'', or sauropods such as ''

'', and ''

Opisthocoelicaudia ''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the head and neck wa ...

''. Adults would have received little competition from small theropods such as the small

'',

troodontid Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil disco ...

s ('' Borogovia'', '' Tochisaurus'', ''

Zanabazar Öndör Gegeen Zanabazar, , , "High Saint Zanabazar"; 1635–1723 (born Eshidorji) was the sixteenth '' Jebtsundamba Khutuktu'' and the first ''Bogd Gegeen'' or supreme spiritual authority, of the Gelugpa (Yellow Hat) lineage of Tibetan Buddhism ...

''),

oviraptorosaur Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or w ...

s (''

Elmisaurus ''Elmisaurus'' (meaning "foot sole lizard") is an extinct genus of caenagnathid dinosaur from the Late Cretaceous Nemegt Formation of Mongolia. It was a theropod belonging to the Oviraptorosauria. Discovery In 1970, a paleontological Polish-M ...

'', ''

Nemegtomaia ''Nemegtomaia'' is a genus of oviraptorid dinosaur from what is now Mongolia that lived in the Late Cretaceous Period, about 70million years ago. The first specimen was found in 1996, and became the basis of the new genus and species ''N. barsbo ...

'', ''

Rinchenia ''Rinchenia'' (named after Byambyn Rinchen) is a genus of oviraptorid dinosaur that lived in Asia during the Late Cretaceous epoch in what is now Mongolia, Nemegt Formation, around 70 million years ago. The type and only known species, ''R ...

'') or ''

Bagaraatan ''Bagaraatan'' (/'ba-ɣa-raa-tan/ meaning 'small' ''baɣa'' + 'carnivorous animal, beast of prey' ''araatan'' in Mongolian) is a genus of theropod dinosaur from the Late Cretaceous period. Its fossils were found in the Nemegt Formation of Mongoli ...

'', sometimes considered a basal

tyrannosauroid Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...

. Other theropods, like the gigantic ''

Therizinosaurus ''Therizinosaurus'' (; meaning 'scythe lizard') is a genus of very large therizinosaurid that lived in Asia during the Late Cretaceous period in what is now the Nemegt Formation around 70 million years ago. It contains a single species, ''Theriz ...

'', might have been

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

, and ornithomimosaurs such as ''

Anserimimus ''Anserimimus'' ( ; "goose mimic") is a genus of ornithomimid theropod dinosaur, from the Late Cretaceous Period of what is now Mongolia. It was a lanky, fast-running animal, possibly an omnivore. From what fossils are known, it probably closely ...

'', '' Gallimimus'', and gigantic '' Deinocheirus'' might have been omnivores that only took small prey and were therefore no competition for ''Tarbosaurus''. However, as in other large tyrannosaurids as well as modern

Komodo dragon The Komodo dragon (''Varanus komodoensis''), also known as the Komodo monitor, is a member of the monitor lizard family Varanidae that is endemic to the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the largest extant ...

s, juveniles and subadult ''Tarbosaurus'' would have filled niches between the massive adults and these smaller theropods.

References

External links

Images and photos
Skeletal image
of ''Shanshanosaurus'' a

Comparison between ''Tarbosaurus'' skulls from specimens of different age group and size
Readable material

at The Theropod Database.

by George Olshevsky (1995). * ''Scienceblogs:'
Juvenile, 5 years old ''Tarbosaurus'' specimen found in Mongolia 2006
{{Taxonbar, from=Q2491 Tyrannosaurids Monotypic dinosaur genera Maastrichtian life Late Cretaceous dinosaurs of Asia Apex predators Cretaceous Mongolia Fossils of Mongolia Nemegt fauna Fossil taxa described in 1955 Taxa named by Evgeny Maleev