Science: The Dinosaur Riddle

What caused the mysterious extinction of the mighty dinosaur some 70 million years ago? Scientists have offered a lengthy catalogue of explanations, ranging from the inadequacy of the dinosaur's brainpower in the face of the earth's changing environment to a burst of lethal radiation from a nearby exploding star. Now a pair of experts have offered some other solutions to the old puzzle:

> Writing in Nature, Robert T. Bakker of Harvard's Museum of Comparative Zoology argues that unlike other reptiles, dinosaurs were probably warm-blooded creatures, like most birds and mammals. He cites, among other arguments, anatomical evidence that some dinosaurs may...