A T. rex skeleton in Belgium. (Photo: Paul Hermans/CC BY-SA 3.0)

A new species of dinosaur shows that Tyrannosaurus rex, the king of the Cretaceous Period, got smarter before it got stronger. 

Scientists announced Monday that a newly-discovered ancestor of the beast, which is believed to have gone extinct around 66 million years ago, shows that T. rex had begun developing predatory skills and a very large brain well before it grew to lengths of up to 40 feet.

“Tyrannosaurs were already hardwired with the sensory arsenal of a top predator before they got to be super giants,” Steve Brusatte, who led the scientists, tells Discovery News.

The new ancestor, called Timurlengia euotica, is about the size of a horse. It was discovered in Uzbekistan and lived over 20 million years before T. rex. 

The evolution in size over the intervening period was relatively quick, Brusatte said, suggesting that a prior mass extinction of predators paved the way for T. rex to take over. 

Though the newly-discovered ancestor was smaller, it still probably isn’t something you’d want to encounter in the wild. Another scientist in the team called it “a nimble pursuit hunter with slender, blade-like teeth suitable for slicing through meat.”