Allosaurus
Allosaurus
Allosaurus was a large bipedal predator for its time. Its skull was light, robust, and equipped with dozens of sharp, serrated teeth. It averaged 8.5 meters (28 ft) in length for A. fragilis, with the largest specimens estimated as being 9.7 meters (32 ft) long. Relative to the large and powerful legs, its three-fingered hands were small and the body was balanced by a long, muscular tail. It is classified in the family Allosauridae. As the most abundant large predator of the Morrison Formation, Allosaurus was at the top of the food chain and probably preyed on large herbivorous dinosaurs such as ornithopods, stegosaurids, and sauropods. Scientists have debated whether Allosaurus had cooperative social behavior and hunted in packs or was a solitary predator that forms congregations, with evidence supporting either side.
Renaming to Antrodemus and early discoveries at Dinosaur National Monument
The many names coined by Cope and Marsh complicated later research, with the situation further compounded by the terse descriptions they provided. Even at the time, authors such as Samuel W. Williston suggested that too many names had been coined. For example, Williston pointed out in (/wiki/1901inpaleontology) that Marsh had never been able to adequately distinguish Allosaurus from Creosaurus. The most influential early attempt to sort out the situation was produced by Charles W. Gilmore in (/wiki/1920inpaleontology). He came to the conclusion that the tail vertebra named Antrodemus by Leidy was indistinguishable from those of Allosaurus and that Antrodemus should be the preferred name because, as the older name, it had priority. Antrodemus became the accepted name for this familiar genus for over 50 years, until James H. Madsen published on the Cleveland-Lloyd specimens and concluded that Allosaurus should be used because Antrodemus was based on material with poor, if any, diagnostic features and locality information. For example, the geological formation that the single bone of Antrodemus came from is unknown.
Renaming to Antrodemus and early discoveries at Dinosaur National Monument
In 1909, Earl Douglass from the Carnegie Museum discovered what should later become Dinosaur National Monument in Utah. Until 2022, Douglass and his team excavated over 700,000 lb (320,000 kg) of fossils of multiple dinosaur species from a single quarry, including several Allosaurus specimens. Among these finds is CM 11844, which was collected between 1913 and 1915 and comprises much of the skeleton and a fragmentary skull. Since 1938, this skeleton is on display at the Carnegie Museum. During the summer of 1924, the University of Utah uncovered DINO 2560, the best preserved Allosaurus specimen known at that time. The skull of this particularly large individual is on exhibit at the Dinosaur National Monument.
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