The Largest Tracksite in North America

The Largest Tracksite in North America. . A famous discovery was made right here along the Purgatoire River! During the Jurassic Period, hundreds of dinosaurs once inhabited this area when it was a vast lake. As they plodded through the mud along the lakeshore, the dinosaurs left behind trails of footprints in the soupy muck. Later, these muddy flats were baked hard in the sun, buried, and later turned to stone. , Today, over 1,300 dinosaur footprints are exposed at the Dinosaur Tracksite, extending nearly a quarter mile across bedrock where they are frozen in time, recording dinosaur behavior from 150 million years ago. , From the deep past of a bygone world, these tracks continue to teach us how dinosaurs lived, and may give us clues about our future. , Preserving Fossil Resources , The Purgatoire River, the same force that unearthed the tracksite, has since begun to erode it away. The US Forest Service preserves the tracksite with erosion control structures made from displaced blocks of the tracksite itself. , Caption: The footprints were made by several kinds of dinosaurs, but mainly huge, long-necked plant-eating sauropods traveling in herds (like Apatosaurus) and prowling meat-eaters (like Allosaurus).