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