T.rex ‘all brawn, little brain’

We know Tyrannosaurus rex was ferocious, with bone-crunching jaws and big slavering teeth. But was the king of the dinosaurs also an intellectual?

This question has divided palaeontologists since a paper last year that argued the predator might have had intelligence comparable to that of a monkey. Now researchers have re-evaluated that data. “It’s an exciting narrative,” said Kai Caspar, of Heinrich-Heine-Universitat Dusseldorf. “Unfortunately it’s unsubstantiated.”

The dispute comes down to how many neurons a T.rex had.

If you assume its skull had a brain similar to that of a bird – its closest living relative – then it was a truly magnificent brain.

With perhaps three billion forebrain neurons, it would have been the skull of an animal that could have culture, could pass on learning and – tiny arms notwithstanding – engage in tool use. That was the argument made last year by neuroscientists at Vanderbilt University in the United States. By looking at the skull cavity of various dinosaurs including T.rex, and mapping that on to those of living relatives, they concluded it had a brain like a modern primate.

Caspar says his new study, published in the Anatomical Record, corrects that idea in two ways. The first regards how much of the skull is brain. While birds pack their skulls with neurons, reptiles such as crocodiles do not. Caspar maintains its brain was more crocodile-like.

The second disagreement comes when assessing its brain density.If the T.rex’s brain was as honed as a bird’s, it might have a billion neurons. If it was like a modern reptile, it would be a third that. His hunch is the latter.

“Just because it was probably similar to reptiles ... does not mean it was dim-witted. Reptiles today perform ... very complex behaviours.”