(CN) — Last year, a study posited a controversial and somewhat unsettling idea: that some dinosaurs, including the mighty Tyrannosaurus rex, were as smart as primates.
But paleontologists, in a study published Monday in The Anatomical Record, pushed back on this idea. They instead argue that T. rex and other dinosaurs were actually just dumb reptiles — and in terms of intelligence, more like the giant crocodiles that preceded them, and less like baboons.
Brazilian neuroscientist Suzana Herculano-Houzel had argued in her 2023 paper that some dinosaur brains were densely packed with neurons, much as baboon brains are.
Her study, published in the Journal of Comparative Neurology, even went so far as to claim that T. rex "had the biological capabilities to use and craft tools," and perhaps even the ability to develop a sort of "culture."
“The possibility that T. rex might have been as intelligent as a baboon is fascinating and terrifying, with the potential to reinvent our view of the past," said Darren Naish, a vertebrate palaeozoologist who worked as a consultant on the Apple TV series "Prehistoric Planet," in a written statement. "But our study shows how all the data we have is against this idea. They were more like smart giant crocodiles, and that’s just as fascinating."
When asked about the velociraptor — the dinosaur smart enough to turn a door knob in the film "Jurassic Park," he said, "Velociraptor and other birdlike dinosaurs proved to be more birdlike, and hence were probably birdlike in intelligence, which means that they were likely about as smart as ostriches and emus."
The paleontologists' research shows that Herculano-Houzel had overestimated dinosaur brain size, and thus its neuron counts as well. They also say that neuron count estimates are not an especially reliable guide to intelligence.
Naish called the 2023 study "way off the mark." Herculano-Houzel did not respond to an email requesting a comment.
Though estimating the brain size of a long-extinct species is a tricky business, the authors of the new paper say it's best to rely on other forms of evidence, like skeletal anatomy, bone histology, the behavior of living relatives and trace fossils.
"We argue that it’s not good practice to predict intelligence in extinct species when neuron counts reconstructed from endocasts are all we have to go on,” said Kai Caspar, a professor of zoology at the University of Düsseldorf and the lead author of the paper, in a written statement.
"Neuron counts are not good predictors of cognitive performance, and using them to predict intelligence in long-extinct species can lead to highly misleading interpretations,” added paleontologist Ornella Bertrand.
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