During the late 19th century era known as the Gilded Age, paleontologists Othniel Charles Marsh and Edward Drinker Cope engaged in a bitter competition to find and describe dinosaur fossils. In trying to outdo each other, they introduced a combined 136 new species that included such well-known genera as Stegosaurus, Triceratops, Diplodocus, Coelophysis, Apatosaurus/Brontosaurus and Allosaurus.
The latter of these was first discovered in Jurassic-aged sediments in Colorado. Countless additional samples were later recovered in Utah, particularly from deposits at the Cleveland-Lloyd Dinosaur Quarry in Emery County.
Othniel Marsh Names Allosaurus
In 1869 Ferdinand Hayden, distinguished for his leadership of several surveying expeditions through the west, acquired a bone from Middle Park, Colorado. Locals referred to the fossil as a petrified horse hoof, but eminent paleontologist Joseph Leidy identified it as a partial vertebra from a dinosaur, referring it in 1870 to the genus Poekilopleuron (spelling it as Poicilopleuron). Later that year Leidy changed his identification, attributing the specimen to a new genus that he named Antrodemus.
Several years later, Marsh sent one of his many fossil diggers to Garden Park, Colorado, north of Canon City, to search for dinosaur remains. Excavating rocks of the Jurassic-aged Morrison Formation, he found several fragmentary bones of ribs, vertebrae, a toe, and an arm, plus a tooth, which appeared to belong to the same animal.
Upon examining the fossils, Marsh believed they came from a previously undescribed species of dinosaur and introduced the name Allosaurus fragilis in 1877. The name Allosaurus is derived from the Greek words meaning "strange (or different) lizard" and refers to the vertebrae that were distinct from those of other dinosaurs then known. The specific name means fragile in Latin and refers to the relatively light-structured vertebrae.
Scientists later realized that Allosaurus was synonymous with Antrodemus; that is, the Allosaurus bones belonged to the same type of animal as those of Antrodemus. Since Antrodemus was coined first, it became the accepted name and was used by scientists for decades.
But in 1976 paleontologist James Madsen, after studying numerous specimens from the Cleveland-Lloyd Dinosaur Quarry in Utah, noted that the original material on which Antrodemus was based was very limited and lacked distinct features. Plus, the precise location at which the material was recovered was unknown. Madsen therefore concluded that Allosaurus, though introduced after Antrodemus, should instead be used.
Through the years scientists have recovered Allosaurus fossils not only in Colorado and Utah, but also South Dakota, Wyoming, Montans, New Mexico, Oklahoma and Portugal. Allosaurus lived about 150 million years ago and was a dominant predator that fed on herbivorous and perhaps other carnivorous dinosaurs.
Allosaurus grew to a length of about 28 feet and weighed perhaps 2200 pounds, though some individuals may have been as long as 40 feet. Like Tyrannosaurus, Allosaurus had large, powerful hind legs but small forelimbs.
The Cleveland-Lloyd Dinosaur Quarry in Emery County, Utah
In 1927 geologists from the University of Utah explored the area around Cleveland, Utah, where sheepherders had stumbled upon a deposit of bones. The university crew recovered between 500-800 bones that year, establishing the site as an important fossil locality.
Years later, in 1939, graduate student William Lee Stokes of Princeton University headed a field camp that spent three summers at the site, excavating another 1200 bones. This effort was financed by lawyer and Princeton graduate Malcolm Lloyd, and the site soon became known as the Cleveland-Lloyd Quarry.
In 1960 Stokes, now working for the University of Utah and with the assistance of Madsen, led a multi-institutional effort to excavate fossils at the quarry. For the next five years the venture uncovered thousands more bones.
Later efforts uncovered even more specimens, and today the Cleveland-Lloyd Quarry is known to contain the highest concentration of Jurassic dinosaurs in the world. In total, diggers have found some 15,000 bones representing at least 14 dinosaur species. A few of the more recognizable beasts include Stegosaurus, Camptosaurus and Haplocanthosaurus. However, the most dominant fossil, represented by at least 46 of the 70 individual animals recovered, is Allosaurus fragilis.
Madsen, inspired by the dominance of Allosaurus fossils at the quarry, proposed in the late 1970s that this dinosaur be recognized as Utah’s official state fossil. Utah’s Division of State History then held a contest at the State Fair in which students voted on the issue, giving the nod to Allosaurus.
In 1988, senator Omar Bunnell introduced a bill to make the designation official. The state legislature passed the bill, and now the Utah Code under Title 63G, Chapter 1, Section 601 (13) recognizes Allosaurus as Utah’s state fossil.
Sources
Marsh, Othniel. 1877. "Notice of New Dinosaurian Reptiles from the Jurassic Formation". The American Journal of Science, Vol. XIV.
Kevin Schindler - I have worked at scientific institutions for more than 20 years written more than 200 articles about science, history, and baseball.
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