The Tarbosaurus bataar was a gigantic predatory dinosaur that dominated the ecosystems of ancient Asia during the Late Cretaceous period. As one of the largest members of the Tyrannosauridae family, this formidable carnivore shared many physical similarities with its famous North American cousin, Tyrannosaurus rex.
Origin and Classification
Tarbosaurus is classified within the sub-family Tyrannosaurinae, establishing it as a close relative to other massive tyrannosaurs. The species Tarbosaurus bataar lived approximately 70 million years ago during the Maastrichtian stage of the Late Cretaceous epoch. Its fossils have been primarily recovered from the Nemegt Formation in Mongolia’s Gobi Desert, with additional fragmentary remains found in parts of China.
The first remains of this dinosaur were discovered during a joint Soviet-Mongolian expedition in 1946. Soviet paleontologist Evgeny Maleev formally named and described the species in 1955, initially classifying it as Tyrannosaurus bataar. Subsequent analysis led to a reclassification, establishing the genus Tarbosaurus, meaning “alarming lizard.” The species name bataar is a misspelling of the Mongolian word for “hero.”
Defining Physical Characteristics
Adult Tarbosaurus were immense, reaching lengths of up to 10 to 12 meters (33 to 39 feet) and weighing an estimated 4 to 5 metric tons. Its overall body plan was that of a powerful bipedal predator, supported by massive hind limbs and a long, heavy tail that served as a counterbalance. The largest known skull of Tarbosaurus measures over 1.3 meters long, rivaling the size of the largest T. rex skulls.
The skull structure was notably narrower, particularly towards the rear, and lacked the robust width that allowed for the forward-facing eyes and binocular vision of T. rex. This narrower structure suggests it was better adapted for a vertical shearing bite force rather than the bone-crushing lateral bite force associated with the North American species.
Its jaws were lined with between 58 and 64 teeth, which is slightly more than the count found in Tyrannosaurus. A unique feature was a locking mechanism in its lower jaw, which provided increased stability during a bite. The forelimbs of Tarbosaurus were proportionally the smallest of all known tyrannosaurids, featuring two functional digits. They were even more diminutive relative to its body size than those of T. rex.
Habitat and Predatory Behavior
Tarbosaurus reigned as the apex predator in the Nemegt Formation, an environment vastly different from the arid Gobi Desert of today. The paleoenvironment was a humid floodplain, characterized by a network of river channels, wet forests, and mudflats. This lush ecosystem supported a diverse array of large herbivorous dinosaurs.
Its diet likely included the large hadrosaur Saurolophus and the long-necked sauropods Nemegtosaurus and Opisthocoelicaudia. The rigid structure of its skull, which transferred stress differently than T. rex, is hypothesized to have been an adaptation for taking down these massive sauropods. Fossil evidence, including bite marks on the gastralia of the giant ornithomimosaur Deinocheirus, suggests that Tarbosaurus focused on accessing the internal organs of its kills.
The Tyrannosaurid Debate
A long-standing controversy revolves around whether Tarbosaurus bataar should be recognized as its own distinct genus or if it is simply an Asian species of Tyrannosaurus. Arguments for lumping the species together, often referring to it as Tyrannosaurus bataar, emphasize the overall similarity in their gigantic size and generalized body plan. They are undeniably sister taxa, meaning they are each other’s closest relatives.
The prevailing consensus maintains Tarbosaurus as a separate genus based on several distinct anatomical features. The primary evidence rests on the cranial differences, particularly the narrower skull structure and the unique jaw-locking mechanism. These differences suggest a separate evolutionary trajectory and a distinct ecological niche, particularly in how they processed their prey. The proportional disparity in forelimb length is a further argument for maintaining the two as separate genera.