by By Will Dunham
WASHINGTON (Reuters) – Even speculating on the physical appearance of a dinosaur – or any extinct animal – based on its fossils is trivial, with so many uncertainties involved. Estimating dinosaur intelligence is exponentially more difficult, given the incomplete factors that contribute to that trait.
A study published last year by Vanderbilt University neuroscientist Suzana Herculano-Houzel that evaluated the intelligence of Tyrannosaurus rex, focusing on estimated brain size and the number of brain neurons, comparable to primates – specifically baboons – provoked agitation in circles scientific. .
Now, an interdisciplinary scientific team has published a rebuttal study, questioning the Herculano-Houzel methodology and challenging its assessment of the intelligence of T. rex and other large dinosaur predators in the dinosaur clade known as theropods.
They suggested instead a more holistic approach to evaluating the brain of a Tyrannosaurus or any extinct animal, taking into account brain size and neuronal count along with other factors such as an animal’s anatomy and ecology, data from living relatives, and fossil evidence how he got on and lived which offers an insight into his life.
“Our main findings are that the brains of most dinosaurs, including T. rex, were comparable in relative size to the brains of living reptiles, such as crocodiles and alligators. In addition, their number of neurons was probably not exceptional, especially for animals of their body mass,” said zoologist Kai Caspar of Heinrich Heine University in Germany, who studies the behavior of living animals and was the lead author of the study published this week in the journal The Anatomical Record.
“What needs to be emphasized is that the reptiles are not as weak-witted as is commonly believed,” said Caspar. “Their behavior can be very complex, and the experimental data we have shows many cognitive similarities between them, mammals and birds. So, although there is no reason to assume that T. rex had primate-like habits , it was certainly a behaviorally sophisticated animal.”
Herculano-Houzel said she stands by her findings and called the new analysis flawed.
“The only thing that is in dispute is what was already at the time of my study: what was really the size of dinosaur brains. Even then, we are talking about the difference between the brain of T. rex a be baboon- or monkey-sized,” said Herculano-Houzel.
“Their conclusion hinges on one very important point: whether theropods like T. rex were related (brain and body size) to their extant cousins ostriches and hot chicks, or to their larger living relatives far, crocodiles. said the first, because I compared ostriches to chickens; now they say the second,” said Herculano-Houzel.
Caspar said the comparison with modern birds was also a key part of the new study.
‘NOT A REAL QUESTION’
Trying to measure information from brain neuron counts is problematic, Caspar said.
“The first obstacle is to estimate the actual size of the brain of the extinct animal in question. This is not a trivial question in dinosaurs. While the brain fills almost the entire skull cavity in birds and mammals, this is not the case for reptilian species, where the brain only fills about 30-50% of the skull cavity,” said Caspar.
“The 2023 study assumed a 100% fill of dinosaurs like T. rex, which was definitely not the case,” said Caspar.
It’s not known how densely packed the neurons were in dinosaur brains, Caspar said.
“However, looking at living animals, we see that neuron count is not a good indicator of intelligence in the first place, even though it may be intuitive at first glance,” Caspar said.
The dinosaurs, apart from their bird descendants, disappeared 66 million years ago after an asteroid hit the Earth. In two centuries of scientific study, dinosaurs have come into better focus, although there are still plenty of uncertainties about Tyrannosaurus and the others.
“Given the size of the brain we found for it, Tyrannosaurus probably had a level of intelligence that we do not see in the modern world: more intelligent than crocodiles, but less intelligent than living birds and typical mammals,” said a paleontologist University Maryland Thomas Holtz. , co-author of the new study.
“Intelligence is one of the hardest things to measure even in modern animals, and a lot of our common assumptions don’t really hold up when you examine what real animals do in real life,” Holtz said.
“So when we try to estimate the intelligence and cognition of ancient animals, we will have some difficulties. It would be nice if we could estimate a single number and solve the entire complexity of an animal’s biology and lifestyle, but nature does not. ” t so.”
(Reporting by Will Dunham, Editing by Rosalba O’Brien)
