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
Jurassic epochs: Early, Middle, and Late. Similarly, in stratigraphy, the Jurassic is divided into the Lower Jurassic, Middle Jurassic, and Upper Jurassic series of rock formations, also known as "Lias", "Dogger" and "Malm" in Europe. The separation of the term Jurassic into three sections originated with Leopold von Buch. The faunal stages from youngest to oldest are: During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico's Yucatan Peninsula. The Jurassic North Atlantic Ocean