The Dry Mesa Quarry was developed by Brigham Young University in the 1970s after Delta rockhound Vivian Jones discovered bones from what turned out to be two new dinosaurs, the Supersaurus and Torvosaurus in the Uncompaghre National Forest.
The quarry, which was active from 1971 until 2000, produced 4,000 bones from 17 different dinosaurs drawn to a water hole in a dry lake by a drought 150 million years ago but died of starvation and dehydration. A brief flash flood then hit the lake bed, burying the skeletons in sandstone.
In addition to the Supersaurus and Torvosaurus, the dinosaurs found at Dry Mesa include the Allosaurus, Apatosaurus, Camarasaurus, Ceratosaurus, Diplodocus, Ankylosaurus, Stegosaurus and Camptosaurus. The fossils at the site also include pterosaurs, birds, crocodiles, fishes and mammals.
Jones and her husband, Daniel, found the Torvosaurus bones in 1971 and the Supersaurus bones in 1972 while rock hunting in Escalanate Canyon about 20 miles southwest of Delta.
Jones contacted paleontologist James Jensen of BYU, who excavated the skeletons and was able to name and describe the two dinosaurs, with the giant, plant-eating Supersaurus replacing the Brachiosaurus, first discovered near Grand Junction, as the largest dinosaur on record with a typical size of 110 feet in length and 35 to 40 tons in weight.
Jensen also reported the discovery of what he called the Ultrasaurus from the same quarry, but the dinosaur turned out to be just another Supersaurus.
The meat-eating Torvosaurus, named in 1979, reached 36 feet in length and 2.2 tons in weight, making it one of the largest carnivores of the late Jurassic period.
Most of the dinosaur bones recovered from the quarry are at BYU, but a sampling of bones from at least a dozen dinosaurs were donated by Jones to the Delta County Historical Society Museum.
The quarry was closed in 2000.
Dry Mesa Quarry
20 miles southwest of Delta
Uncompahgre National Forest