A year ago, corporate media promoted the provocative claim that dinosaurs like Tyrannorsaurus rex had so many neurons they had to be substantially more intelligent than assumed, since these high neuron counts could directly inform on intelligence, metabolism and life history.

They even added that T. rex was monkey-like in some of its habits and may even have used cultural transmission of knowledge as tools. Corporate media sells ads so they love such 'scientists are baffled by' narratives and a scenario where dinosaurs could be ruling on other planets. Other scientists were instead baffled that it got by peer-review.

Now another group re-examined the brain size and structure in dinosaurs and say they were not as as advanced as monkeys, they were on par with crocodiles and lizards.

Brain to body mass relationship in land-living vertebrates. Dinosaurs have brain to body size ratios similar to those of living reptiles. Credit: Cristian Gutierrez-Ibanez

The authors say their conclusion is different because the techniques used to predict both brain size and neuron numbers in dinosaur brains relied on assumptions about brain size in dinosaurs, and the number of neurons their brains contained, that were unrealistic. Those are fighting words in science, yet such things happen far too often in academic-driven corporation journals. Paleontology just isn't overrun with sloppy methodology that bypasses skeptical peer review the way epidemiology and the social science are.

The reason the new claims about dinosaur intelligence were so provocative is that palaeontologists and biologists have examined dinosaur brain size and anatomy using mineral infillings of the brain cavity, termed endocasts, as well as the shapes of the cavities themselves. Because that is all quantifiable, there can some inference on behavior and lifestyle but caution was warranted.

Then last year, just like a few years back when we were told there were dinosaurs ruling on other planets, there was an outlier claim about the size of the forebrain and thus neuron counts as well. Because they were only writing for journalists and not other scientists, they 'suggested' neuron count estimates are a reliable guide to intelligence but that is not true. Neurons alone, ignoring multiple lines of evidence, including skeletal anatomy, bone histology, the behavior of living relatives, and trace fossils, is not how a generally conservative field of science makes conclusions.

“Neuron counts are not good predictors of cognitive performance, and using them to predict intelligence in long-extinct species can lead to highly misleading interpretations,” stated Dr. Ornella Bertrand of Institut Català de Paleontologia Miquel Crusafont.

Dr Darren Naish of the University of Southampton said, “The possibility that T. rex might have been as intelligent as a baboon is fascinating and terrifying, with the potential to reinvent our view of the past. But our study shows how all the data we have is against this idea. They were more like smart giant crocodiles, and that’s just as fascinating.”