Scientists have discovered that Tyrannosaurus rex is not as intelligent as previously claimed

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 such as T. rex had an exceptionally large number of neurons and were much more intelligent than assumed. It has been claimed that these high numbers of neurons could give direct information about intelligence, metabolism and life history, and that Tyrannosaurus was ape-like in some of its 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.

But the new study published in anatomical record, Featuring 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 Ibáñez (University of Alberta) and Dr. Grant Hurlburt (Royal Ontario Museum) takes a closer look at the techniques used to predict brain size. And the 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.

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, so neurons also mattered. In addition, they showed that estimates of the number of neurons are not a reliable guide to intelligence.

The team argues that in order to reliably reconstruct the biology of long-extinct species, researchers must 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.

Dr Caspar explained: “We are of the opinion that it is not good practice to predict intelligence in extinct species when the number of neurons reconstructed from endophytic fungi is all we have to go on.”

Dr Ornella Bertrand (Institut de Paleontologia Miquel Crosafont of Catalonia) added: “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.”

“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,” Dr. Naish concluded. “But our study shows how all our data contradicts this idea. They were more like giant, intelligent crocodiles, and that's equally remarkable.”