Contents

12 February 1999
Vol 283, Issue 5404

About The Cover

Cover image expansion

COVER The head of an alligator snapping turtle (Macroclemys temminckii), about actual size. This heavily armored species resembles an alligator when partly submerged. The similarity has been thought to be the result of adaptive convergence. However, data from multiple genes now support an evolutionary link between turtles and crocodilians, challenging the long-held view that birds are the closest living relatives of crocodilians. See page 998. [Photo: Wayne Van Devender]