Ever since Massachusetts farmer Pliny Moody unearthed fossil footprints while plowing his father's field in 1802, North Americans have discovered dinosaurs — often by accident, and occasionally in their own back yards.

School kids on a fishing trip in Alberta, Canada, put down their lines to explore the badlands and stumbled upon what looked like a rather large leg bone. Encouraged by their their teacher, the students contacted the Royal Tyrrell Museum, which excavated the fossil and the rest of a Tyrannosaurus rex skeleton, now called Black Beauty.

Hikers enjoying the vistas in a New Mexico wilderness area noticed some large and curious bones protruding from the ground. They notified paleontologist Dave Gillette, who then undertook the massive task of uncovering what became the longest dinosaur skeleton ever found: the only known specimen of earth-shaking Seismosaurus.

In February 2000, while clearing his property in St. George, Utah, for a development, retired optometrist Sheldon Johnson overturned a rock slab with a backhoe and exposed the tracks of Jurassic theropods. He invited experts to come in and study the tracks and plans to preserve the tracks for posterity.

These stories have happy endings to those who value preserving paleontological heritage for future generations. But meanwhile, fossil theft is rife on Western public lands. And even uninformed amateurs may unwittingly damage or destroy precious fossil evidence to satisfy their curiosity. Stories like that of Sue, the T. rex skeleton sold at auction for $8.4 million, feed a market for finding and selling dinosaur bones. (Sue, at least, ended up on permanent display at Chicago's Field Museum of Natural History.)