Killing a Legend (cont'd)

"People don't like it much," he says. "But we're doing science here. It's not an opinion poll. This is based on an accumulation of the evidence. It's just hard to change your mind when you grow up with the idea that this is a big, nasty predator."

When Horner talks about Tyrannosaurus rex, it's hard not to pay attention. He's paleontology curator of the Museum of the Rockies in Bozeman, Mont., which accounts for 11 of the roughly two dozen T. rex specimens ever found. Teams that Horner led into the Hell Creek region of eastern Montana found eight of the giants in the past two years as part of an unprecedented effort in paleontology.

The five-year Hell Creek Project, the largest and most comprehensive ever undertaken anywhere, is reconstructing the paleoecosystem, with its dinosaurs, plants, mammals and mollusks, of the Hell Creek geological formation. This remarkable block of sediments — 300 feet (91 meters) from top to bottom and fairly bristling with fossils — spans the final chapter of the dinosaurs' tale from 68 million to 65 million years ago.

This remarkable formation lies open, like a window into the distant past, in the countless canyons and gullies that slice through the rugged and supremely isolated project area. The wind and precious rain continually expose new bits of ancient bone, potential jewels for the prospecting paleontologists, students and volunteers who hike the unending hills to collect clues to a world far different from ours.

Besides the astounding eight T. rex specimens, the project, now in its third year, has discovered an array of exotic creatures, including 50 horned Triceratops, plant-eaters that weighed 6 tons each; a half-dozen ostrich-like dinosaurs called Ornithomimids; a huge duckbill dinosaur, Edmontosaurus; an Ankylosaurus, a bulky herbivore with armored plates and a tail club; and a Torosaurus, a 4-ton beast with an enormous skull ringed by a bony frill.

The Hell Creek region has a long history as a haven of dinosaurs. Fabled dinosaur hunter Barnum Brown found the first Tyrannosaurus rex near the study area in 1902. Henry Osborn, Brown's boss at the American Museum of Natural History, named and described it — as a supreme predator. The T. rex of most of the past 100 years — Osborn's vicious killer — towered upright, its tail dragging the ground, its horrible mouth gaping open.

Morphological studies of the past few decades found a big problem with that: Standing upright would have broken T. rex's back. The giant must actually have stood bent over at the waist, its tail stretched out behind as a counterweight.