Contents

24 February 2006
Vol 311, Issue 5764

About The Cover

Cover image expansion

COVER Artist's reconstruction of Castorocauda lutrasimilis diving into water. Castorocauda is an omnivorous mammal from the Middle Jurassic (~164 million years ago) and is the earliest known semi-aquatic animal in the mammalian lineage. See page 1123. Image: Mark A. Klingler, Carnegie Museum of Natural History