Across Fourmile Creek was the site of a major dinosaur excavation. In 1954, Edwin Delfs, a zoology student at Yale University, joined the Cleveland Museum of Natural History on a fossil-hunting expedition throughout Colorado and Utah. After receiving a tip from geology students from Louisiana State University, Delfs guided his group of high school students to Cañon City. There they discovered several large bone fragments and filed for a mining claim to keep the fossils from uranium prospectors. The fragments lay in a mudstone layer sandwiched between two hard sandstone layers, and as the crew excavated the mudstone they supported the upper sandstone with large timbers, creating a tunnel-like cavity in the cliff. During the next three years, Delfs and his inexperienced group bulldozed the hillside and blasted the sandstone with dynamite. The fossils were packed into field jackets, hard plaster shells wrapped around them for protection. Fourmile Creek sometimes flooded suddenly, and moving jackets weighing up to 2,500 pounds across the creek was as dangerous as extracting them from the rock. Wooden rafts towed by a small bulldozer carried the jackets across. In the end, the crew excavated about 60 percent of a Haplocanthosaurus, a large long-necked sauropod dinosaur. Known as "Happy," this remarkably well-preserved skeleton is now on display at the Cleveland Museum of Natural History. Of the four known Haplocanthosaurs discovered, the one from this quarry is the only specimen complete enough to be mounted in a museum, although no Haplocanthosaurus skull has yet been found.