In 1900, paleontologist Elmer Riggs and crew, from the Field Museum of Natural History in Chicago, found the first known "Brachiosaurus altithorax" at a location later called "Riggs Hill," located off what is now State Highway 340 in Grand Junction. Led here by communications with Dr. S.M. Bradbury of Grand Puns, Riggs had heard that ranchers had been collecting fossils around the area for 20 years. In 1901, Riggs and crew found nearly two thirds of an "Apatosaurus excelsus" skeleton (commonly known as a "Brontosaurus") on the northeast side of Dinosaur Hill, in Fruita. This is still considered to be one of the finest specimens known. Later, other sauropod bones were also found, which eventually led to the landmark's name. The animals were from the late Jurassic Age (150 million years ago) and within the Morrison Formation.