A new species of tyrannosaur adds to the fearsome group of dinosaurs to which Tyrannosaurus rex belonged. Scientists found its 90-million-year-old bones in the harsh deserts of Uzbekistan.
The newly described species, Timurlengia euotica, is an oddball.
The horse-sized dinosaur resembles earlier, smaller tyrannosaurs. Yet it’s large brain and advanced ears—their outlines preserved in a skull fragment – mirror those of later tyrannosaurs like T. rex.
“Timurlengia is truly a curveball,” says Thomas Carr of Carthage College, who wasn’t involved with the study. “I had to readjust the way I thought about tyrannosaurs. It’s a weirdo.”
The new species, described Monday in the Proceedings of the National Academy of Sciences, could also help untangle one of the most frustrating questions in dinosaur evolution: How and why did tyrannosaurs get so big?
Tyrannosaurs first appear in the fossil record about 170 million years ago, and until about 100 million years ago, they scampered about on the ecological margins, some no bigger than dogs.
But by the late Cretaceous – about 80 million years ago – tyrannosaurs such as T. rex had ballooned into some of the biggest, most intimidating land predators ever to walk the planet. Head to tail, they could get as long as a bus, and their enormous heads and powerful jaws could generate bites with nearly 13,000 pounds of force.
“The funny thing is that T. rex is such a pop star,” says Lawrence Witmerof Ohio University, who wasn’t involved with the study. “None of us can even remember a time when we didn’t know about Tyrannosaurus. But the reality is that how [it] evolved is a bit of a mystery.”
What’s more, T. rex wasn’t just big. It was gifted.
“Contrary to what people learned in the first Jurassic Park movie, T. rex had acute senses,” says study co-author Hans-Dieter Sues of the Smithsonian National Museum of Natural History.
“It clearly had very keen eyesight, a spectacularly keen sense of smell, and keen hearing.”
Its killer senses stemmed from its impressive brain: T. rex’s two olfactory lobes – the brain regions devoted to smell—were each the size of a grapefruit. And its long, looped ear canals helped it hear the low-frequency sounds emitted by distant prey’s footsteps.
“It was sort of a superpredator,” says Sues.
But paleontologists have struggled to pin down how tyrannosaurs got brainier and brawnier, largely because the fossil record between 100 and 80 million years ago, when small tyrannosaurs would have evolved into giants, is so sparse.
“At that particular point in time, sea levels were very high,” says Sues. “We just didn’t have the record from the land animals.”
[Header image: Todd Marshall]