An Intricate Mind

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For years, scientists thought that dinosaurs were big but dumb.

But now, some researchers believe that some dinosaur brains were so complex and densely packed with neurons that they nearly resembled the noggins of modern primates, according to a new but controversial study.

Neuroanatomist Suzana Herculano-Houzel and her colleagues have even proposed that certain members of the extinct species were smart enough to use tools or form groups, the Washington Post reported.

For their paper, they sought to measure the density of neurons in the dinos’ cortex – the wrinkly area of the outer brain critical to most intelligence-related tasks.

Because dinosaur brains are difficult to get, the team analyzed the brain cases of some of the species – including Tyrannosaurus rex – and compared them with a massive database of bird and reptile brain masses.

They then devised an equation that correlated an animal’s brain mass with the approximate amount of neurons in the cerebrum, which comprises the cortex.

Their findings showed that the brains of theropod dinosaurs – which include T. rexes and velociraptors – nearly follow the same rules as warm-blooded modern birds. Meanwhile, the brains of sauropod dinosaurs, such as gigantic Brachiosaurus, resemble those of modern cold-blooded animals, according to Science magazine.

For example, Herculano-Houzel observed that the T. rex brain had as many as three billion neurons – comparable to a baboon’s brain. Another theropod, the deadly Alioramus, meanwhile, had more than one billion, similar to a capuchin monkey.

“I have a whole newfound respect for T. rex,” Herculano-Houzel told Science. “Something that big with those teeth that had the cognitive capacity, numberwise, of a baboon … that is legit scary.”

While some researchers and paleontologists praised the study for shedding some light on dinosaur smarts, others were careful in suggesting that the extinct creatures were intelligent enough to use tools.