What was the level of intelligence of the T-Rex?

How smart was he? Tyrannosaurus Rex That depends on who you ask.

Last year, this iconic dinosaur got the most attention of its life when neuroscientist Susana Herculano-Hauser calculated that just the front part of the fearsome reptile’s brain contained 3.3 billion neurons (nerve cells). Put your brains into it T. rex brain is equivalent to that of a modern baboon.

Indeed, the theory suggests that ancient predators may have had the intelligence to develop culture and make tools, but the claim has raised some eyebrows and sparked skepticism.

With the new calculations, Significantly reduced number of neurons.

The new study suggests that dinosaurs had nearly 360 million neurons in their telencephalons, a part of the forebrain that plays a role in sensing, thinking, and coordinating movement. If this is true, this low number is likely due to the fact that the telencephalons of dinosaurs had nearly 360 million neurons. T. rex This is the mental level of a crocodile, not a baboon. New figures published by an international research team on April 26th show that: Autopsy report.

Herculano Hauser of Vanderbilt University in Nashville, Tennessee, isn’t convinced by the new calculations, which she says contain a “catastrophic error” that has led to the undercount.

To calculate how many neurons an animal has, we need to know how densely packed those brain cells are. This can be difficult because neuron density varies widely between animals. Also, brain cells are The fossils are not well preserved. So when scientists study extinct animals, they need to estimate neuron density based on their modern relatives.

And here is the problem: T. rex belongs to a group of dinosaurs known as theropods. They are related to both reptiles and birds. However, these two groups differ greatly in neuronal density. Reptiles have fewer neurons per unit volume of brain than birds. Calculating the number of neurons in extinct theropods: T. rex Researchers must decide whether their research will be based on birds, reptiles, or a mix of both.

Bird brain or reptile head?

In a 2023 study, Herculano-Hauser worked out the relationship between brain size and body mass for about 30 species of dinosaurs. She then looked at how these figures compared to modern birds and reptiles. Using ancient bird families suggested that theropod brains were similar to bird brains. So she ran calculations using the density of modern birds.

Even if birds were living dinosaurs, that assumption is wrong, says Cristian Gutiérrez Ibáñez, a comparative neuroscientist at the University of Alberta in Edmonton, Canada, where he studies the brains of many different creatures. Birds have different brain-size-to-body-weight ratios, so in the new study, his team took into account many more birds alive today. T. rex The brain-to-body ratio of is close to that of scaly reptiles.

Herculano Josell’s study inflated the number of neurons in another way, Gutiérrez Ibáñez says: She hypothesized that dinosaur brains took up the entire skull. As the name suggests, this part of the skull contains the brain. But unlike modern birds, dinosaur brains T. rex And many other dinosaurs also floated in liquid, just like modern crocodiles.

Recalculating T. rex “When we base our estimates of brain volume on a smaller portion of the braincase, the number of neurons drops dramatically,” Gutierrez-Ibáñez said. Estimates for the telencephalon dropped from 3.3 billion to 1.2 billion. When we use reptile neuron densities, the number drops even further, to between 245 and 360 million.

Herculano-Hauser counters that her study does take into account that dinosaur brains did not fill the skull. Moreover, she argues, it makes no sense to consider the different body-to-brain ratios of modern birds. Her study only considered birds that are closest to dinosaurs. By throwing in birds with very different body-to-brain ratios, like pelicans and penguins, she says, the new study has drawn the wrong conclusion. T. rex They looked like modern-day Crocs.

Brain and Behavior

In any case, T. rex The number of neurons a dinosaur had may not be a good measure of their overall intelligence, says Amy Baranov, an evolutionary biologist at the Johns Hopkins University School of Medicine in Baltimore, Maryland, who was not involved in either study.

Neuronal density T. rex Because dinosaurs had similar abilities to primates, these cells likely helped them move their large bodies and gather sensory information. For example, T. rex Baranov points out that the frontal lobes of the brain were huge. Even if the cerebrum was packed with neurons, he says, many of them were likely devoted to processing smells. And scientists don’t yet have much evidence that these early dinosaurs used their brains to fashion tools or develop cultures.

Gutierrez Ibáñez agrees: “Having the same number of neurons as a primate doesn’t make you a primate,” he says. To suggest that these dinosaurs used tools or were as intelligent as primates “seems like a big leap.”

Still, Herculano-Hauser’s work is helpful: “I’m really grateful for the original study because it sparked a discussion,” Baranov says. “If people aren’t willing to share their data, we can’t move science forward.”

Source: www.snexplores.org