Image of a T. rex skeleton at the Senckenberg Museum in Frankfurt, Germany. T. rex lived during the Late Cretaceous Period (about 66 million years ago) and was exclusive to western North America. Credit: Kai R. Caspar
Dinosaurs were as intelligent as reptiles but not as intelligent as apes, as previous research suggests.
An international team of paleontologists, behavioral scientists and neurologists re-examined the size and structure of dinosaur brains and concluded that they behaved more like crocodiles and lizards.
In a study published last year, it was claimed that dinosaurs like T. rex had an exceptionally high number of neurons and were significantly more intelligent than previously thought. It has been claimed that this high number of neurons can provide direct information about intelligence, metabolism and the history of life, and that T. rex rather resembled a monkey in some of his habits. The cultural transmission of knowledge as well as the use of tools were cited as examples of cognitive traits they might have possessed.
Criticism of neuron counting methodology
However, the new study, published in The anatomical file, involving Hady George from the University of Bristol, Dr Darren Naish (University of Southampton) led by Dr Kai Caspar (Heinrich Heine University) with Dr Cristian Gutierrez-Ibanez (University of Alberta) and Dr Grant Hurlburt (Royal Ontario Museum), takes a closer look at the techniques used to predict both brain size and the number of neurons in the brains of dinosaurs. The team found that previous assumptions about dinosaur brain size and the number of neurons contained in their brains were unreliable.
Relationship between brain and body mass in terrestrial vertebrates. Dinosaurs like T. rex have a brain-to-body size ratio similar to that of living reptiles. Credit: Cristian Gutierrez-Ibanez
The research follows decades of analysis in which paleontologists and biologists examined the size and anatomy of dinosaur brains and used that data to infer their behavior and lifestyle. Information about dinosaur brains comes from the mineral fillings of the brain cavity, called endocasts, as well as the shape of the cavities themselves.
The team found that their brain size had been overestimated – particularly that of the forebrain – and so the number of neurons was also large. Furthermore, they show that estimates of neuron numbers are not a reliable guide to intelligence.
Recommendations for future research
Reliably reconstructing the biology of long-extinct species speciesAccording to the team, researchers should examine several lines of evidence, including skeletal anatomy, bone histology, behavior of living relatives and trace fossils. “It is best to determine the intelligence of dinosaurs and other extinct animals using numerous data sources ranging from gross anatomy to fossil footprints, rather than relying solely on estimates of neuron numbers,” explained Hady from the Bristol School of Earth Sciences.
Dr Kai Caspar explained: “We argue that it is not good practice to predict intelligence in extinct species when the number of neurons reconstructed from endocasts is all we have. »
“The number of neurons is not a good predictor of cognitive performance, and their use to predict intelligence in long-extinct species can lead to very misleading interpretations,” added Dr Ornella Bertrand (Institut Català de Paleontologia Miquel Crusafont).
“The possibility that T. rex could have been as intelligent as a baboon is fascinating and terrifying, with the potential to reinvent our view of the past,” concluded Dr. Darren Naish. “But our study shows how all the data we have goes against this idea. They looked more like giant, intelligent crocodiles, and that’s just as fascinating.
