Mammals’ brains got bigger to handle sense of smell
Mammals have the largest brains relative to body size out of all the organisms on Earth. In addition, only mammals have a neocortex, the outer layer of the cerebral hemispheres that participates in higher functions like sensory perception, refined motor coordination, and language. Researchers are interested in figuring out how mammals evolved such large and complex brains. Studying brain evolution has been limited by the rarity of intact skulls and a shortage of techniques that can analyze the interior of those fossils without destroying them.
Mammals evolved roughly 200 million years ago, either before or during the Early Jurassic period. Researchers have access to jaws and teeth from that period, but they rarely come across full skulls. To get information on the brains enclosed by those rare skulls using traditional methods, scientists would have to risk damaging the fossils. Recently, lead researcher Timothy Rowe and his colleagues overcame this problem. They applied high-resolution X-ray computed tomography to nondestructively visualize the interior of ancient skulls.