Big Tarbosaurus Specimens

The largest known skull of T. bataar compared to a human.

In the Nemegt formation, Tarbosaurus is abundantly preserved. Researchers have found over 100 specimens. Knowledge of Tarbosaurus, however, is hampered by the paucity of described, adult material. The type, PIN 551-1, is thought to represent a mature individual but is an exception. Generally, only immature individuals have been published.

In part, the scarcity of adult specimens may be due to taphonomy. Nemegt tyrannosaurs often faced droughts. Juveniles, which heated up more quickly, may have suffered the highest mortality. But much of the reason may be economic.

Compared to western institutions, the paleontological museums and universities of Poland, Mongolia and Russia have limited resources. Cleaning and preparing a specimen, especially a large dinosaur, is costly. Often, it is beyond the means of researchers in Warsaw, Ulaanbataar and Moscow. With little funding, they can not afford to prepare, and hence publish, many of their bigger specimens. PIN 551-1 was an exception because it consists of just an incomplete skull. The postcrania was either absent, or not collected.

Despite lack of formal description, there have been reports of large Tarbosaurus individuals. One, nicknamed "teresa," is said to be complete, 12m long and with a 1.5 meter skull.

A large Tarbosaurus skull, photographed in situ.

A skull of 1.5 meters suggests a fully grown Tarbosaurus was as large as T. rex. It may have equalled the tyrant king in other ways, such as expansion of the posterior part of the skull and the degree to which its eyes faced forward, possibly conferring stereopsis. An adult Tarbosaurus might resemble Tyrannosaurus sufficiently to be put in the same genus, vindicating the view of Rozhdestvensky and Greg Paul (the latter in PDW). In addition, if larger than thought, the apex predator may have overcome the formidable Nemegtosaurus, Therizinosaurus and Deinocheirus.

Considering the potential value of the larger, unprepared T. bataar specimens, in clarifying taphonomic, paleoecological and taxonomic questions, more funding should be made available to institutions possessing such specimens.

Teeth of the top Nemegt predator, exposed during excavation.