Cretaceous Park; December 2002; Scientific American Magazine; by Sonya Senkowsky; 2 Page(s)

From a bluff-side vantage point 500 feet above the braids and twists of Alaska's Colville River, we notice that a line of brush along a distant gravel bed is, in fact, moving. "Caribou," someone says-hundreds of them, in fact, surging along the river in an improbably large, swirling mass. For expedition leader Anthony R. Fiorillo, it's enough to prompt a paleontological daydream: What if, 70 million years ago, a similar grouping of dinosaurs had passed this way? And what if those dinosaurs had met with a sudden, mass death, as caribou sometimes do? That might explain the bonanza of horned dinosaur fossils in the tundra underneath our feet-possibly the densest concentration of saurian fossils in the world.

Fiorillo-curator of earth sciences at the Dallas Museum of Natural History-first brought his team to this remote, roadless spot on the edge of the National Petroleum Reserve above the Arctic Circle to recover the skull of a type of horned dinosaur known as a pachyrhinosaurus, or "thick-nosed dinosaur," a member of the family Ceratopsidae. It didn't take much digging to realize that fossilized dinosaur bones were nearly as ubiquitous here as the Arctic's summer sun. By expedition's end, the team members, also from the University of Alaska-Fairbanks and Southern Methodist University, had turned up evidence of eight pachyrhinosaurs from a quarry not 50 feet square.