How brainy was Tyrannosaurus rex? It depends on who you ask.
The finding raised eyebrows — and doubts. Any suggestion that these dinosaurs were as smart as primates “seems like a large leap,” says Cristián Gutiérrez-Ibáñez, a comparative neuroscientist at the University of Alberta in Edmonton, Canada. “Having the same number of neurons as a primate does not make you a primate.”
Now, Gutiérrez-Ibáñez and colleagues have come up with a much more conservative neuron count. The T. rex telencephalon, a part of the forebrain involved in sensory, cognitive and motor functions, had closer to 360 million neurons, researchers report April 26 in the Anatomical Record. The new estimate suggests that T. rex’s forebrain is more similar to that of modern crocodiles than of primates, the researchers say.
Calculating how many neurons an animal has requires knowing how densely packed the brain cells are. That can be tough not only because neuron density varies widely between animals, but also because these brain cells aren’t well preserved in the fossil record (SN: 11/14/13). When scientists look at extinct animals, they must use the neuron densities of modern relatives as proxies.
2024-05-16 08:00:00
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