
Scientists used very high-resolution scanning to study the skulls of two of the earliest known mammal species.
Comparing the shape of their brain cases to those of slightly earlier animals, or "pre-mammals", revealed that the first brain areas to over-develop were those associated with the sense of smell.
The findings are published in Science.
An improved sense of smell may have allowed our tiny, furry ancestors to hunt at night.
The researchers were able to create 3D images of prehistoric animals' brains using the latest computed tomography, or CT, scanning methods.
"Before CT, one had to break open a fossil to get to the internal anatomy," explained Professor Timothy Rowe from the University of Texas at Austin, one of the researchers involved in the study.
"[This technique] is non-destructive, so we can measure internal anatomy in ways that were never before possible."










