This Pebble Turns Out to Be a Fossilized Dinosaur Brain

And iguanodons may have been smarter than we thought.

The fossilized brain of an Iguanodon. (University of Cambridge)

A couple of weeks ago I wrote in a post that scientists should go hunting for a preserved dinosaur brain. Sure enough, it turns out the first one has recently been found! It was not preserved in amber, and it wasn’t from one of the most intelligent of dinosaurs. Nevertheless, it provides some interesting insights.

Martin Brasier from the University of Oxford in England and his colleagues reported the remarkable preservation of brain tissue in an iguanodon-type dinosaur. The authors recognized what looked like a brown pebble as a dinosaur brain after applying some sophisticated techniques such as scanning electron microscopy and computed tomography (CT). They were even able to distinguish internal subdivisions. For example, they could identify the tough membranes (meninges) that enveloped and supported the ancient brain and could trace the locations of blood vessels that had been replaced by the mineral siderite.

What was most interesting was that the dinosaur brain seemed to be closely packed in the skull, comparable to the brains of humans and birds, and not loosely fitted as the brains of reptiles are, which suggests a higher intelligence than previously thought. The authors admit that this conclusion is not firm, however, as the tight packing may just be an artifact of the fossilization process. Still, the team’s analysis of the forebrain and hindbrain support the idea of greater behavioral complexity in the iguanodon, which was a herbivore roaming a river valley about 133 million years ago.

Herbivores are not known to be particularly smart. A cow doesn’t need to be clever—it just has to be able to defend itself and run away, whereas predators need to anticipate the next move of their prey to make a catch. Even more intelligence is required for a social predator like a wolf or a velociraptor, because these animals have to anticipate the actions of their prey as well as coordinate with their fellow animals in the hunting party. This type of behavior, plus the use of tools—necessary due to our more vulnerable bodies—propelled us humans to become as intelligent as we are.

If further studies show that the iguanodon was smarter than previously thought, one might wonder how much smarter a velociraptor or troodon might have been. Would some of them even have used tools in their hunt?

About Dirk Schulze-Makuch
Dirk Schulze-Makuch

Dirk Schulze-Makuch is a Professor at the Technical University Berlin, Germany and Adjunct Professor at Arizona State University and Washington State University. He has published seven books related to astrobiology and planetary habitability.

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