Evolution and Diversity

Abstract

If we stepped out of a time machine 65 million years ago, at the end of the Cretaceous period, we would find ourselves in a completely unfamiliar world. The seas would be warm and placid, Antarctica would be covered in forest, there would be no Atlantic or Pacific oceans, and Europe would be just one big archipelago. We would be hard pushed to tell herbivores from carnivores and completely unable to point to the ancestors of the shrews or the whales. All these mammals looked pretty much the same, as they were all members of the superorder of Laurasiatheria—one of the four main branches of the mammalian family tree. Amongst these creatures were those that would one day become bats, but since there are no fossil records from them, we have no idea what they might have looked like.