For most people, the Jurassic period conjures up images of huge dinosaurs chomping their way through lush vegetation and each other.
But mammals and their immediate ancestors were also around 201 to 145 million years ago, just not as spectacular as we are now.
Early Jurassic mammals were thought to have been confined to the ecological margins, eating whatever insects they could find. However, this was also the time when new mammal characteristics – such as better hearing and teeth capable of precise chewing – were developing. So, if the earliest mammals were all small generalized insectivores, where was the competition driving the evolution of such features?