Tarbosaurus (meaning "terrifying lizard") is a genus of tyrannosaurid theropod dinosaur that flourished in Asia between 70 and 65 million years ago, at the end of the Late Cretaceous Period. Fossils have been recovered in Mongolia with more fragmentary remains found further afield in parts of China. Although many species have been named, modern paleontologists recognize only one, T. bataar, as valid. Some experts contend that this species is actually an Asian representative of the North American genus Tyrannosaurus; if true, this would invalidate the genus Tarbosaurus altogether.
Tarbosaurus and Tyrannosaurus are considered closely related genera, even if they are not synonymous. Alioramus, also from Mongolia, is thought by some authorities to be the closest relative of Tarbosaurus. Like most known tyrannosaurids, Tarbosaurus was a large bipedal predator, weighing more than a ton and equipped with dozens of large, sharp teeth. It had a unique locking mechanism in its lower jaw 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 criss-crossed by river channels. In this environment, it was an apex predator at the top of the food chain, probably preying on other large dinosaurs like the hadrosaur Saurolophus or the sauropod Nemegtosaurus. Tarbosaurus is very well-represented in the fossil record, known from dozens of specimens, including several complete skulls and skeletons. These remains have allowed scientific studies focusing on its phylogeny, skull mechanics, and brain structure.
It is believed that Tarbosaurus was, in fact, T. rex that migrated from North America to Asia through some sort of "land bridge" that connect the two continents during the Late Cretaceous period (around 70-66 million years ago).
Discovery and naming[]
Holotype skull PIN 551–1, Museum of Paleontology, Moscow
While its fossils were first unearthed in 1946 during a joint Soviet-Mongolian expedition to the Gobi Desert in the Ömnögovi Province of the Nemegt Formation in Mongolia, the genus Tarbosaurus (from the Ancient Greek for "Terror" or "Alarming Lizard") was formally named nine years later in 1955 by Soviet paleontologist Evgeny Maleev. Research by scientists suggests that Tarbosaurus is very close to Tyrannosaurus, but there is argument on whether or not the two species are in the same genus, which if true the genus would be renamed to Tyrannosaurus bataar. Other than size, for which Tarbosaurus measured between 10.06 and 12.3 m (33 and 40 ft) in length, grew to stand between 3 and 4 m (9 and 13 ft) tall at the hips, and between 4 and 6 t (8,818 and 13,227 lb) in weight - still making it one of the largest tyrannosaurs and theropod dinosaurs - the main notable differences between them is that Tarbosaurus has a thinner jaw, more heavily serrated teeth, smaller arms relative to its size, a wider gape, and somewhat weaker bite force than its North American cousin. These are due to Late Cretaceous Asia lacking large amounts of ceratopsians and ankylosaurs that Tyrannosaurus preyed on, and instead tooth marks show Tarbosaurus was optimized for hunting large hadrosaurs.
Description[]
Size comparison of specimens representing various growth stages
Although smaller than Tyrannosaurus, Tarbosaurus was one of the largest tyrannosaurids. The largest known individuals were between 10 and 12 meters (33 to 40 ft) long. The mass of a fully grown individual is considered comparable to or slightly smaller than Tyrannosaurus, often estimated to be around 5–6 metric tons. The largest known Tarbosaurus skull is more than 1.3 meters (4 ft) long, larger than all other tyrannosaurids except Tyrannosaurus.
Labelled skull diagram of specimen ZPAL MgD−I/4
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 of Tyrannosaurus. Large fenestrae (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 Gorgosaurus and Alioramus.
Most of its teeth were oval in cross section, although the teeth of the premaxillae at the tip of the upper jaw had a D-shaped cross section. This heterodonty is characteristic of the family. The longest teeth were in the maxilla (upper jaw bone), with crowns up to 85 millimeters (3.3 in) long. In the lower jaw, a ridge on the outer surface of the angular bone articulated with the rear of the dentary bone, creating a locking mechanism unique to Tarbosaurus and Alioramus. Other tyrannosaurids lacked this ridge and had more flexibility in the lower jaw.
Skeletal reconstruction (ZPAL MgD I/4)
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, 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, 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 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 to the head and torso and placed the center of gravity over the hips.
Paleobiology[]
Skull of juvenile (top, MPC-D 107/7), and adult (bottom, ZPAL MgD I/4)
Although many specimens of this genus has been found, little definite data is confirmed on the dinosaur as of 1986, though it is presumed and has been shown to share many characteristics with other tyrannosaurids.
During studies of the animal, the upper jaw proved very interesting, as it possessed more than 20 extremely large, knife-shaped teeth. The skull in general seems to have many similarities with its North American cousin, Tyrannosaurus rex, prompting many to place it in the Tyrannosaurus genus (the resulting designation would then be Tyrannosaurus bataar). The close similarities have also 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. The discovery of Lythronax further cements this relationship, as it shows Tarbosaurus is most closely related to Tyrannosaurus, and Zhuchengtyrannus while Lythronax stands as the sister taxon to this clade.
Only one species of Tarbosaurus, T. bataar, has been officially established. Tarbosaurus is very well-represented in the fossil record, known from dozens of specimens, including several complete skulls and skeletons. These remains have allowed scientific studies focusing on its phylogeny, skull mechanics, and brain structure. Although smaller than Tyrannosaurus, Tarbosaurus was one of the largest tyrannosaurids.
The largest known individuals were about 11m long and 5.5 tonnes in weight. Tarbosaurus is unique among Tyrannosaurids in that it possesses a locking mechanism in its jaws; possibly an adaptation for hunting sauropods. This locking mechanism also made the theropod's skull more rigid as a result.
While juvenile tyrannosaurids in general are rare, a skeleton of a very young Tarbosaurus (estimated to be two or three years of age) indicates they had very different niches from the adults and may have been nocturnal, based on measurements of their sclerotic rings. Whether the adults were nocturnal as well is not known.
Skin impressions are known from Tarbosaurus, and show the animal had non-overlapping scales. However, fossil poachers destroyed the impressions, and as such they can no longer be studied. Footprints attributed to the genus are also known from the Nemegt Formation.
Paleoecology[]
Cretaceous-aged dinosaur fossil localities of Mongolia; Tarbosaurus was collected in area A (left).
Tarbosaurus fossils have been found primarily in the Nemegt Formation of Mongolia, and are believed to be early Maastrichtian in age (circa 70 mya). At the time, Mongolia was a seasonal floodplain on the edge of a desert that was prone to long dry seasons and short wet seasons. The resulting environment may have looked similar to the modern Okavango Delta of Africa. Regardless, it was an environment capable of supporting a wide array of large dinosaur species.
Tarbosaurus would have shared the Nemegt with many genera and species of animals. While Tarbosaurus was at the top of the food chain, it also shared its environment with other predators, such as the smaller Alioramus, another tyrannosauroid belonging to the Alioramini, the dromaeosaurid Adasaurus, and troodontids such as Borogovia, Tochisaurus, and Zanabazar, oviraptorosaurs Elmisaurus, Nemegtomaia, Rinchenia or Bagaraatan, (which may actually be a basal tyrannosauroid rather than an oviraptorosaur). Other theropods, like the gigantic Therizinosaurus, and ornithomimosaurs such as Anserimimus, Gallimimus, and gigantic Deinocheirus dwelled here as well. Other dinosaurs of note that resided in the Nemegt included Saurolophus (also native to North America), ankylosaurids such as Tarchia and Saichania, the pachycephalosaurid Prenocephale, and the titanosaurid Nemegtosaurus (which may or may not be synonymous with Opisthocoelicaudia). All would have been potential prey for adult Tarbosaurus, while adolescent Tarbosaurus may have been forced to compete with Alioramus for food due to occupations of a similar niche.
Classification[]
Diagram showing the differences between a generalised Tarbosaurus (A) and Tyrannosaurus (B) skull
Tarbosaurus is classified as a theropod in the subfamily Tyrannosaurinae within the family Tyrannosauridae. 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 Albertosaurus and are known for their robust build with proportionally larger skulls and longer femurs 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. A 2003 cladistic 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 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 Tyrannosauridae based on the phylogenetic analysis conducted by Loewen et al. in 2013.
| Tyrannosauridae |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
JPInstitute.com Description[]
This was a very close relative of Tyrannosaurus rex that lived in China during that Late Cretaceous period. Originally called Tarbosaurus when it was discovered in 1955, it was later renamed Tyrannosaurus baatar after studies and comparisons of the fossils determined that they were from the same family.
This dinosaur is good example of how international cooperation can greatly benefit science, and it also helps to show how genus and species are related. Tyrannosaurus baatar is the same genus, but a different species.
See Tyrannosaurus rex for more information.
Appearance in other media[]
Jurassic Park[]
- Tarbosaurus was in the The Dinosaurs of Jurassic Park: The Lost World written by Don Lessem. Although it only appeared in various video games including Jurassic World: The Game, Jurassic World: Alive and Jurassic Park III: Park Builder and toy merchandise across the Jurassic Park Franchise, Tarbosaurus made it's first ever canonical appearance in the 2022 animated Netflix interactive special Jurassic World Camp Cretaceous: Hidden Adventure. It acts as the main antagonist of the story with it hunting down the campers from Jurassic World: Camp Cretaceous on Isla Nublar, where in the ending (dependent on the viewer's choices) can either fight the Tyrannosaurus rex or a Carnotaurus. The design of the dinosaur received negative criticisms due to looking too similar to the iconic design of the Tyrannosaurus, being oversized and having spikes on it's back similar to that of the Giganotosaurus appearing in Jurassic World: Dominion, despite having no scientific evidence of Tarbosaurus ever having them. Eventually the dinosaur made it's way as a DLC into Jurassic World: Evolution 2.
 |
Read more Tarbosaurus on Jurassic Park Wiki |
We're Back! A Dinosaur's Story[]
It appears in Your Pet Dinosaur: An Owner's Manual.
Links[]
References[]
- https://www.nhm.ac.uk/discover/dino-directory/tarbosaurus.html
- https://australian.museum/learn/dinosaurs/fact-sheets/tarbosaurus-bataar/
- https://www.smithsonianmag.com/science-nature/you-say-tyrannosaurus-i-say-tarbosaurus-142897656/
- https://www.app.pan.pl/archive/published/app48/app48-161.pdf
- https://www.livescience.com/20540-tarbosaurus-tyrannosaurus-difference.html
- http://www.gondwanastudios.com/info/tarb.htm
- http://www.dinosaur-world.com/tyrannosaurs/tarbosaurus_bataar.htm
- https://blog.everythingdinosaur.co.uk/blog/_archives/2007/08/27/3194599.html
- https://www.researchgate.net/publication/226337077_A_new_study_of_the_brain_of_the_predatory_dinosaur_Tarbosaurus_bataar_Theropoda_Tyrannosauridae
- https://www.researchgate.net/figure/The-skeleton-of-tarbosaurus-Tarbosaurus-bataar-The-largest-predator-was-up-to-12-14-m_fig8_338327588
- https://www.researchgate.net/figure/Juvenile-Tarbosaurus-bataar-MPC-D-107-7-A-photograph-of-the-specimen-prior-to_fig1_232865497
- https://www.researchgate.net/publication/26871213_A_long-snouted_multihorned_tyrannosaurid_from_the_Late_Cretaceous_of_Mongolia
- https://a-dinosaur-a-day.com/post/107163811085/tarbosaurus-bataar
- https://www.biologiatropical.org/blog/the-mysterious-twin-dinosaurs
- https://www.researchgate.net/figure/Mounting-a-Tarbosaurus-skeleton-in-the-Paleontoo-logical-Museum_fig4_263760683
- https://www.researchgate.net/publication/232865497_Cranial_Osteology_of_a_Juvenile_Specimen_of_Tarbosaurus_bataar_Theropoda_Tyrannosauridae_from_the_Nemegt_Formation_Upper_Cretaceous_of_Bugin_Tsav_Mongolia