Elmer S. Riggs Riggs' assistant, H. William Menke, found the first known skeleton of the giant sauropod dinosaur "Brachiosaurus altithorax" from near Grand Junction, Colorado. At the end of the 1900 field season Riggs' found a specimen of "Apatosaurus" near Fruita, a few miles from the Brachiosaurus site. This specimen was excavated during the 1901 field season, and was put on display in 1908 at the Field Museum. From these specimens he named "Brachiosaurus" and Brachiosauridae, and presented evidence that "Apatosaurus" and "Brontosaurus" were the same genus of dinosaur. He also proposed that sauropods were terrestrial animals, based on their limb structure, but
Apatosaurus on the anterior end. The pelvic girdle includes the robust ilia, and the fused (co-ossified) pubes and ischia. The femora of "Apatosaurus" are very stout and represent some of the most robust femora of any member of Sauropoda. The tibia and fibula bones are different from the slender bones of "Diplodocus" but are nearly indistinguishable from those of "Camarasaurus". The fibula is longer and slenderer than the tibia. The foot of "Apatosaurus" has three claws on the innermost digits; the digit formula is 3-4-5-3-2. The first metatarsal is the stoutest, a feature shared among diplodocids. The name "Apatosaurus ajax" was