Tarbosaurus

Tarbosaurus was a large theropod that lived in Asia during the Late Cretaceous period, around 75–70 million years ago. It was very similar to Tyrannosaurus rex in many ways but had some notable differences. T. rex had a wider skull and body, while Tarbosaurus actually had proportionally smaller arms - the smallest of any tyrannosaur. Currently, only one species is recognised: T. bataar. Thankfully, it is known from several relatively complete skeletons.

The name Tarbosaurus means "alarming lizard." It was first discovered in the Gobi Desert of Mongolia in the 1940s. At first, scientists thought the fossils might belong to Tyrannosaurus, the well-known predator from North America, and several different names were proposed as more skeletons were found. Over time, however, it became clear that these remains all belonged to the same animal. The species was eventually named Tarbosaurus bataar - with bataar being a misspelling of the Mongolian word baatar, meaning "hero." The error was not deliberate, but once a scientific name is formally published, it usually cannot be easily changed, so the misspelling remains part of the official name.

There was long debate over whether Tarbosaurus should be classified as its own genus or as an Asian species of Tyrannosaurus. While some paleontologists still use the name Tyrannosaurus bataar, most research today treats Tarbosaurus as a distinct genus. More than 30 specimens have been discovered, including multiple skulls and several nearly complete skeletons. These finds show that Tarbosaurus was a large, two-legged predator with a massive head and strong jaws, occupying the top of the food chain in its Late Cretaceous environment.

Tarbosaurus was a massive predator, slightly smaller on average than Tyrannosaurus rex but still among the largest tyrannosaurs. The largest known specimen measured around 10 m in length, stood about 3 m tall at the hips, and may have weighed up to 5 tonnes. Most adults were somewhat smaller, though still imposing animals. Its skull could reach 1.35 metres in length, making it second in size only to T. rex among tyrannosaurs. Skin impressions reveal a covering of small, non-overlapping scales, and fossilized footprints show fine details of the texture on its feet, including marks left as the scales slid into soft ground. These traces suggest Tarbosaurus had a tough, scaly hide typical of large theropods, well-suited to life as an apex predator. Whether it had feathers is unclear.

The skull of Tarbosaurus was tall like that of Tyrannosaurus rex, but it was noticeably narrower toward the back. Because of this, its eyes faced more to the sides, meaning it likely didn't have the same strong depth perception as its North American cousin. Large openings in the skull helped reduce weight and provided space for jaw muscles, while its jaws held around 58–64 teeth - the higher end of this being slightly more than T. rex. Most of these teeth were oval in shape, but the ones at the front were more D-shaped, a common feature among tyrannosaurs. The longest teeth reached about 8.5 cm in length. A unique locking joint in the lower jaw, shared only with Alioramus, made the jaw more rigid than in other tyrannosaurs, which may have helped it grip prey more firmly.

The rest of Tarbosaurus's skeleton matched the typical build of a large tyrannosaur. It had a big head balanced by a long, heavy tail, an S-shaped neck, and powerful hind legs that supported its weight on two feet. Its arms were extremely short, proportionally the smallest of any known tyrannosaur, with only two working clawed fingers and a reduced third bone in some specimens. Its legs were long and muscular, ending in three-toed feet suited to carrying its massive frame. This body structure, with the tail acting as a counterbalance, helped keep the animal stable and allowed it to move efficiently for its size.

The structure of its skull shows that Tarbosaurus had a more rigid head and jaws than its North American relatives. The bones of its upper jaw were locked together in a way that would have allowed it to handle powerful bite forces without damaging its skull. A similar locking mechanism was present in the lower jaw. These features may have been adaptations for hunting the massive sauropods that lived alongside it, allowing Tarbosaurus to deliver strong, stable bites into very large prey.

Bite marks on the bones of hadrosaurs, sauropods, and other dinosaurs show that Tarbosaurus actively fed on large herbivores. Its bite force is estimated to have reached 8,000 to 10,000 pounds per square inch, strong enough to crush bone. Some fossils suggest it sometimes scavenged carcasses as well, carefully biting and dragging at specific areas to access meat and marrow. Taken together, the evidence indicates Tarbosaurus was a powerful and versatile predator, capable of both hunting and scavenging within its ecosystem.

Most Tarbosaurus fossils have been found in the Nemegt Formation of the Gobi Desert in southern Mongolia, dating to around 70 million years ago. At that time, the landscape was shaped by large rivers, floodplains, and shallow lakes. The climate was warm and generally humid, though there were also seasonal dry periods. Forests of conifers and other trees grew along the waterways, while ferns, reeds, and other plants covered the ground. This mix of habitats created a rich environment capable of supporting many kinds of large animals.

The Nemegt ecosystem included fish, turtles, crocodilians, birds, pterosaurs, and a wide range of dinosaurs. Tarbosaurus was the top predator in this environment, most likely hunting large plant-eating dinosaurs such as the hadrosaur Saurolophus and the sauropods Nemegtosaurus and Opisthocoelicaudia. Smaller carnivorous dinosaurs, including its relative Alioramus, probably focused on smaller prey, while young Tarbosaurus may have occupied those middle roles in the food chain. This diverse and well-watered ecosystem would have provided ample opportunities for a large predator to thrive.