T. rex an intellectual? Well d’oh

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

T. rex had a brain that was more like a crocodile than a bird.

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

This question has divided ­palaeontologists since a paper was published last year that argued the predator might have had intelligence comparable to that of a monkey. It was, the authors of that study maintained, a philosopher king.

Researchers have now re-­evaluated that data and their findings are disappointing for those who liked the idea that behind the dinosaur’s sharp teeth lay a sharp mind.

“It’s an exciting narrative,” said Kai Caspar, from Heinrich-Heine-Universitat Dusseldorf.

“If you work on T. rex, you might want these opportunities to make it an even more interesting story. Unfortunately, it’s un­substantiated.”

The dispute comes down to how many neurons a T. rex had. Estimating that in turn comes down, in part, to what modern species it is most like. If you assume that a T. rex’s skull was filled with 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, that could pass on learning and that could engage in tool use.

That was the argument made last year by a team of neuroscientists from Vanderbilt University in the US. By looking at the skull cavity of various dinosaurs including T. rex, and mapping that on to those of living relatives, they concluded it actually had a brain similar to a modern primate’s.

As lead author Suzana Herculano-Houzel put it: “Something that big with those teeth that had the cognitive capacity … of a ­baboon ... that is legit scary.”

Dr Caspar does not dispute the scariness of the T. rex, but his study, published in the Anatomical Record, is, he believes, a corrective to the idea that scariness came with notable cleverness.

Working in a cross-disciplinary team, he and his colleagues identified two distinct areas of ­disagreement with Professor ­Herculano-Houzel. The first regards how much of the skull is actually brain. While modern birds pack their skulls with neurons, reptiles such as crocodiles do not.

Most of their skull is not brain at all.

Dr Caspar maintains its brain looked a lot more crocodile-like than bird-like. “If you look at its morphology and its traits, you can imagine it as some kind of a mosaic of avian and reptilian,” he said. “So it was warm-blooded and it grew very fast like a bird. But if we look at, for instance, the brain morphology, then it resembled a crocodile.”

This would imply just a third of the skull was filled, reducing the estimate to a billion neurons.

“Why should we assume that an essentially reptilian-looking brain in the T. rex had avian neuron densities?” Dr Caspar said.

None of this, he said, should diminish the majesty of the T. rex – just remind us that before we were rulers of the planet other species had their own ways of triumphing.

The Times