This March 4, 2016 photo provided by the Smithsonian Institution shows Hans Sues, Chair, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution holding a cast (right hand) of a Tyrannosaurus Rex tooth for comparison with an actual tooth of the new tyrannosaur Timurlengia euotica, catalog number 538157, from the Late Cretaceous Period that was found in the Kyzylkum Desert, Uzbekistan.
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For all its fame in pop culture, paleontologists know very little about how the T. rex came to be.
For the last 20 million years of the Age of Dinosaurs, giant tyrannosaurs sat high on the top of the global food chain thanks to their enormous size and sharp senses. As such, it would have been faster than T. rex, and likely terrorized the duck-billed dinosaurs with which it shared the hot, lush environment of mid-Cretaceous Uzbekistan.
The comparatively tiny Timurlengia euotica – yet to receive the notoriety and catchy nickname of its larger descendant – was similar in size to a horse as opposed to the elephant-sized T-rex. This earlier dinosaur lived about 90 million years ago, south of what is now the Aral Sea. Then there is a fossil gap which means that the only evidence of tyrannosaurs comes later, when they had evolved into huge predators.
The partial skull is a T. rex relative called Timurlengia and it is the first well-preserved tyrannosaur braincase from the mid-Cretaceous period.
“Only after these ancestral tyrannosaurs evolved their clever brains and sharp senses did they grow into the colossal sizes of T-rex”.
Some of the fossils found were part of the prehistoric animal’s skull, particularly the braincase.
The brain case in particular was a slam-dunk for researchers.
The team took the fossil and analyzed it against a database of other tyrannosaurs, showing that its brain and ear are almost identical to the T. rex’s, only smaller.
The finding, he said, is a new indication that tyrannosaurs got smart before they got big. T. rex reached about 42 feet (13 meters) and 7 tons.
The fossils also indicate that Tyrannosaurs had advanced cognitive abilities and could hear low-frequency sounds. Timurlengia had a long cochlea too. “Like at a murder scene”, Brusatte said, “one clue is better than none”. “It was part of the toolkit that makes these things such great predators”. Did Timurlengia have three claws like older tyrannosaurs, for instance, or only two like the bigger, advanced forms? Sinuses in the middle ear aren’t quite as specialized as those in the later dinosaur’s head. Weighing up to 600 pounds, the Timurlengia is a member of the tyrannosaur family, but not an ancestor of the T. rex, scientists said.
This suggests that this dinosaur lineage developed its keen hunting senses first, and its giant size later.
“The fossil record just stops”, Brusatte said.
Brusatte acknowledged the limits of what can be inferred from a single species in a single location.
Many questions remain, though. Researchers recently studied the fossils and have published the results of their study, saying the creature – which has been dubbed Timurlengia euotica – was about the size of a modern horse and holds signs about how such a small species evolved into the massive Tyrannosaurus Rex.
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“Its contribution to our knowledge of sensory adaptation in tyrannosaurs will become clearer with more detailed studies of the brain cavity and sensory systems of more primitive tyrannosaurs in particular, and with more quantitative analytical approaches”.
