“It was just a smart crocodile, but that’s just as fascinating”

Big, strong and supreme, the T. rex probably had all kinds of impressive qualities, but intelligence wasn’t one of them, we always thought. Until a study last year suddenly concluded that the supreme dinosaur was much smarter than previously assumed, even comparable to monkeys. However, a new study undermines that idea.

An international team of paleontologists, behavioral scientists and neurologists has re-examined the brain size and structure of dinosaurs and concludes that the largest animals Earth has ever known behaved more like crocodiles and lizards. In terms of intelligence, this has little to do with monkeys.

Use of tools
Back to the study from last year then. It stated that dinosaurs, such as T. rex, had an exceptionally large number of neurons, making them much more intelligent than previously thought. This large number of neurons would provide information about the intelligence, metabolism and life history of the animals. The T. rex would therefore be much more intelligent than previously thought and more ape-like when it comes to its habits and behavior. The cultural transmission of knowledge and tool use were cited as examples of the dinosaur’s cleverness.

Unreliable conclusions
But it turns out to be different. A new research team zoomde in on the techniques used to predict brain size and number of neurons in the dinosaur brain and found that the previous conclusions are unreliable. To this end, they compared decades of studies by paleontologists and biologists on the dinosaur brain and brain anatomy. They used this data to infer the animals’ behavior and lifestyle. This information about the dinosaur brain comes from the minerals in the brain cavity, called the endocast, but also from the shape of the cavity itself.

Brain size overestimated
The researchers discovered that brain size has been overestimated, especially that of the forebrain, an important part of the brain, consisting of the cerebrum and, for example, the pituitary gland and the hypothalamus. The number of neurons is also lower than claimed in the previous study. Moreover, the current study shows that the number of neurons does not even provide a reliable picture of intelligence.

A T. rex skeleton in the Senckenberg Museum in Frankfurt, Germany. The T. rex lived at the end of the Cretaceous period, about 66 million years ago, and was only found in western North America. Image: Kai R. Caspar

To reconstruct the biology of a long-extinct species, scientists must conduct research in several ways, it sounds. The anatomy of the skeleton is important, but also the bone composition, fossils and the behavior of living relatives. “The best way to determine the intelligence of dinosaurs and other extinct species is to use multiple lines of evidence, ranging from gross anatomy to fossil footprints, rather than just relying on an estimate of the number of neurons,” explains one of the researchers. researchers.

Bad research
Another states: “We argue that it is not good research practice to determine the intelligence of an extinct species solely from neuron counts reconstructed from skulls.” And again: “Neuron counts are not good predictors of cognitive performance, and using this data to assess the intelligence of an extinct species can lead to wildly misleading interpretations.”

The researchers are therefore very critical of their colleagues, whose conclusions made headlines worldwide last year. “The possibility that the T. rex is as intelligent as a baboon is fascinating and terrifying. It would mean that we would have to revise our view of the past. But our study shows how all the data we have goes against this idea. The dinosaurs were more like big smart crocodiles and that is just as fascinating,” he concludes.