Alan Turner is Professor of Vertebrate Paleontology at John Moores University in Liverpool, England, and former senior curator of paleontology at the Transvaal Museum in Pretoria, South Africa. He is the author, with Mauricio Ant�n, of The Big Cats and Their Fossil Relatives(Columbia). Mauricio Ant�n is a paleontological artist based at the National Museum of Natural Sciences in Madrid. His work has appeared in National Geographicand Natural History,among other magazines. He has collaborated with the Discovery Channel and the BBC, most recently for the series Walking with Prehistoric Beasts.He is the author, with Jordi Agust�, of Mammoths, Sabertooths, and Hominids(Columbia).