A newly discovered tyrannosaur species called Timurlengia euotica sheds light on how the Tyrannosaurus rex and its close relatives became the dominant predator. The study published in the Proceedings of the National Academy of Sciences reveal that the tyrannosaurus already had keen senses and cognitive functions like the ability to hear low-frequency sounds to hunt prey efficiently even before they became giants.

“The ancestors of T. rex would have looked a whole lot like Timurlengia, a horse-sized hunter with a big brain and keen hearing that would put us to shame,” explains lead researcher Steve Brusatte. “Only after these ancestral tyrannosaurs evolved their clever brains and sharp senses did they grow into the colossal sizes of T. rex. Tyrannosaurs had to get smart before they got big.”

Scientists also believe that tyrannosaurs suddenly became giants within only 70 million years. With these traits, they dominated the Late Cretaceous Period when other carnivorous dinosaurs already went extinct.

Reconstruction of the new tyrannosaur Timurlengia euotica. Painting by Todd Marshall/Smithsonian Institution

Reconstruction of the new tyrannosaur Timurlengia euotica. Painting by Todd Marshall/Smithsonian Institution

Through reconstruction of the brain based on CT scans of its skull, the researchers discovered that the Timurlengia’s senses were highly developed. This horse-sized predator was a fast runner thanks to its long legs and weighed up to 600 pounds (272 kg).

“Timurlengia was a nimble pursuit hunter with slender, blade-like teeth suitable for slicing through meat,” adds Hans Sues, chair of the Department of Paleobiology at the Smithsonian’s National Museum of Natural History. “It probably preyed on the various large plant-eaters, especially early duck-billed dinosaurs, which shared its world. Clues from the life of Timurlengia allow us to fill in gaps and better understand the life and evolution of other related dinosaurs, like T. rex.”

The first tyrannosaurs lived around 170 million years ago during the Jurassic period. They were barely bigger than a human and only became massive like the T. rex 100 million years later, at the end of the Late Cretaceous Period.

The researchers studied fossils between 1997 and 2006 and went into missions in the Kyzylkum Desert of Uzbekistan. They say that this is a good spot to discover fossils because many of the dinosaurs from the Cretaceous period originated here.

“Central Asia was the place where many of the familiar groups of Cretaceous dinosaurs had their roots,” says Sues. “The discoveries from the Kyzylkum Desert of Uzbekistan are now helping us to trace the early history of these animals, many of which later flourished in our own backyard in North America.”