Scientific American (september 1999)

UNSTABLE SOLAR SYSTEMS • WHAT SCIENTISTS THINK ABOUT GOD SPINAL CORD INJURIES: New hope for treating paralysis SEPTEMBER 1999 $4.95 www.sciam.com A kinder, gentler dinosaur? Don’t count on it. COPYRIGHT 1999 SCIENTIFIC AMERICAN, INC . September 1999 FROM THE EDITORS 4 LETTERS TO THE EDITORS 6 Vo l u m e 2 8 1 Breathing Life into Tyrannosaurus rex Numb e r 3 42 Gregory M. Erickson The popular conception of T.rex as the ultimate bloodthirsty hunter is as much a product of artistic license as of science.Only in recent years have paleontologists begun to reconstruct a more rounded view of how these dinosaurs lived. The evidence suggests that T. rex had a flexible appetite and a sociable streak (but watch out for those teeth). 50, 100 AND 150 YEARS AGO 10 The Teeth of the Tyrannosaurs 50 William L. Abler NEWS AND ANALYSIS Uneasy sleep (page 24) Modern analysis of tyrannosaur teeth illustrates how chillingly well suited they were to stripping flesh and crushing bones.And as if the bite weren’t bad enough, toxic bacteria living on the teeth may have poisoned what the T.rex didn’t kill outright. The Dechronization of Sam Magruder 52 George Gaylord Simpson IN FOCUS The Cassini probe’s flyby of Earth prompts antinuke protests. 13 SCIENCE AND THE CITIZEN New data paint an ever more puzzling picture of our universe . . . . Proteins and the immune system . . . . Gorillas in the Bronx . . . . Dangerous dead rattlesnakes. . . . U.S. immigration.... FAA battles birds. In this excerpt from a novel by one of the 20th century’s greatest evolutionary biologists,a time traveler to the Cretaceous struggles to elude lumbering cold-blooded predators. With