New research reveals that dinosaurs were not as intelligent as we thought

Photograph of a T. rex skeleton at the Senckenberg Museum in Frankfurt, Germany. Tyrannosaurus rex lived at the end of the Cretaceous period (about 66 million years ago) and was found exclusively in western North America. Credit: Kay R. Caspar

Dinosaurs were as intelligent as reptiles but not as intelligent as apes, as previous research suggests.

An international team of paleontologists, ethologists and neurologists has re-examined the size and structure of the brain in dinosaurs and concluded that they behaved like crocodiles and lizards.

In a study published last year, it was claimed that dinosaurs love it T-Rex They had an exceptionally large number of neurons and were significantly more intelligent than expected. It has been claimed that these high numbers of neurons could directly benefit intelligence, metabolism, and life history T-Rex He resembled a monkey in some of his habits. The cultural transmission of knowledge as well as the use of tools have been cited as examples of cognitive traits they may have possessed.

Critique of neuron counting methodology

But the new study published in Anatomical record, in which Hadi George from the University of Bristol, Dr. Darren Naish (University of Southampton) and led by Dr. Kai Kaspar (Heinrich-Heine University) with Dr. Cristian Gutierrez Ibanez (University of Alberta) and Dr. Grant Hurlburt (Royal Ontario Museum) take a closer look at the techniques used. To predict brain size and numbers of neurons in dinosaur brains. The team found that previous assumptions about brain size in dinosaurs, and the number of neurons their brains contained, were not reliable.

The relationship between brain and body mass in land-dwelling vertebrates. Dinosaurs like T. rex had brain-to-body size ratios similar to those of living reptiles. Credit: Cristian Gutierrez Ibanez

This research comes after decades of analysis in which paleontologists and biologists examined dinosaur brain size and anatomy, and used this data to infer behavior and lifestyle. Information about dinosaur brains comes from the mineral fillings of the brain cavities, called endocasts, as well as the shapes of the cavities themselves.

The team found that the size of their brains was exaggerated – especially the size of the forebrain – and therefore their neurons also mattered. In addition, they showed that estimates of the number of neurons are not a reliable guide to intelligence.

Recommendations for future research

To reliably reconstruct the biology of long-extinct organisms ClassifyThe team believes that researchers should consider multiple lines of evidence, including skeletal anatomy, bone histology, behavior of living relatives, and trace fossils. “The intelligence of dinosaurs and other extinct animals is best determined using a variety of pieces of evidence ranging from gross anatomy to fossil footprints rather than relying on estimates of the number of neurons alone,” explained Hadi, from Bristol's School of Earth Sciences.

“We are of the opinion that it is not good practice to predict intelligence in extinct species when the population of neurons reconstructed from endogenous cells is all we have to go on,” explained Dr. Kai Kaspar.

“Neuron numbers are not good predictors of cognitive performance, and using them to predict intelligence in long-extinct species can lead to very misleading interpretations,” added Dr. Ornella Bertrand (Instituto de Paleontologia Miquel Crosafont of Catalonia).

Dr Darren Naish concluded: “The possibility that T. rex could be as intelligent as a baboon is both fascinating and terrifying, with the potential to reinvent our view of the past.” “But our study shows how all our data contradicts this idea. They were more like giant, intelligent crocodiles, and that is equally remarkable.”

Reference: “How Intelligent Was T. Rex?” Testing Claims of Extraordinary Cognition in Dinosaurs and Applying Neuron Number Estimates in Paleontological Research” by Kay R. Caspar, Christian Gutierrez Ibáñez, Ornella C. Bertrand, Thomas Carr, Jennifer A. D. Colburn, and Arthur Erb , Hadi George, Thomas R. Holtz, Darren Naish, Douglas R. Willey, and Grant R. Hurlburt, April 26, 2024, Anatomical record.
doi: 10.1002/ar.25459