How brainy was Tyrannosaurus rex? It depends on who you ask.
Last year, the iconic dinosaur received the glow up of a lifetime. Neuroscientist Suzana Herculano-Houzel calculated that the fearsome reptile had 3.3 billion neurons — nerve cells — in just one part of the front of its brain. The discovery seemed to put the brainpower of T. rex’s forebrain on a par with that of modern baboons.
In fact, it suggested the ancient predator might have had the mental hardware to develop culture and make tools. But that claim raised some eyebrows — and doubts.
A new set of calculations has now spat out a much lower neuron count.
Dinos had closer to 360 million neurons in the telencephalon, this new study suggests. That part of the forebrain plays a role in sensing, thinking and coordinating motion. If true, this lower count would put T. rex on the mental level of crocodiles, not baboons. An international team of researchers shared the new count April 26 in The Anatomical Report.
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Those new calculations don’t convince Herculano-Houzel, who works at Vanderbilt University in Nashville, Tenn. There’s a “fatal mistake” here, that leads to the lower count, she says.
To calculate how many neurons an animal has, you must know how closely packed those brain cells were. And that can be tough because neuron density varies widely across animals. Also, brain cells aren’t well preserved in fossils. So when scientists study extinct animals, they must estimate neuron densities based on their modern relatives.
And here lies the issue: T. rex belongs to a group of dinosaurs known as theropods. It’s…
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