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Elmer Riggs' Discovery at Riggs Hill
In 1900, Elmer Riggs, a paleontologist at Chicago's Field Columbian Museum, set out to the Grand Valley to collect dinosaurs. Led here through correspondence from Dr. S.M. Bradbury of Grand Junction, Riggs was inspired by the news that ranchers had been collecting fossils in this area since it was first settled in the 1880s.
On the south slope of this hill in rocks of the Jurassic-age Morrison Formation, Riggs and his field assistants discovered and excavated a previously unknown dinosaur. Riggs assigned the name of Brachiosaurus altithorax (deep-chest arm-lizard) because the front legs were much longer than those in the back and the ribs were nearly 9 feet long. In honor of Riggs' discovery, this hill was named after him, and the site of his quarry is marked with a stone monument.
The dinosaur specimen was discovered on July 4, 1900, but work on it did not begin until three weeks later because Riggs and his crew were finishing work at another site near what is now the east entrance to Colorado National Monument. Riggs recognized very quickly that what they had found was at the time the largest dinosaur known. It remained the largest known for 70 years. The crew took about six weeks to dig up the dinosaur, and by mid-September they were on their way back to Chicago.
Brachiosaurus was a gigantic (43-ton) sauropod dinosaur distantly related to Apatosaurus (Brontosaurus). Unlike most sauropods, however, the front legs of Brachiosaurus were very long, its tail relatively short, its chest very deep, and its neck rather long as well. These characteristics and the fact that its teeth were those of a plant-eater suggest that Brachiosaurus was the Late Jurassic equivalent of a giraffe, feeding high in the treetops. Brachiosaurus is still one of the rarest dinosaurs in the Morrison Formation, but it has also been found in Jurassic rocks as far away as Tanzania in eastern Africa.
In 1937 on the northwest slope of this hill, Edward Holt discovered partial skeletons of Allosaurus and Stegosaurus. Hoping the area would become a natural research center, Holt left the bones in the rock. Unfortunately, the bones and other scientific information have been lost through vandalism.
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