Mammals first evolved large brains to enable stronger sense of smell

A new study by paleontologists from The University of Texas at Austin, Carnegie Museum of Natural History and St. Mary's University in San Antonio has indicated that mammals first evolved their characteristic large brains to enable a stronger sense of smell.

This latest study is the first to use CT technology, similar to medical scanners, to reconstruct the brains of two of the earliest known mammal species, both from the Jurassic fossil beds of China.

The 3D scans revealed that even these tiny, 190-million-year-old animals had developed brains larger than expected for specimens of their period, particularly in the brain area for smell.

According to the study, other factors leading to larger brains in early mammals included greater tactile sensitivity and enhanced motor coordination. Fossils of some of the earliest mammals, such as Hadrocodium, bore full coats of fur, explaining the need for enhanced tactile sensitivity.

"I have spent years studying these fossils, but until they were scanned it was impossible to see the internal details," said Zhe-Xi Luo, curator and associate director for research and collections at the Carnegie Museum of Natural History.

"I was absolutely thrilled to see what the brains of our 190-million-year old relatives were like," added Luo.

The study has been published in the journal Science.