page_title: Albertosaurus
section_title: Dry Island bonebed
hierarchical_section_title: Albertosaurus / Discovery and naming / Dry Island bonebed
caption_attribution_description: English: Albertosaurus teeth - Royal Tyrrell Museum
context_page_description: Albertosaurus is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 70 million years ago. The type species, A. sarcophagus, was apparently restricted in range to the modern-day Canadian province of Alberta, after which the genus is named, although an indeterminate species has been discovered in the Corral de Enmedio and Packard Formations in Mexico. Scientists disagree on the content of the genus, with some recognizing Gorgosaurus libratus as a second species.
  As a tyrannosaurid, Albertosaurus was a bipedal predator with tiny, two-fingered hands and a massive head that had dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. While Albertosaurus was large for a theropod, it was much smaller than its larger and more famous relative Tyrannosaurus rex, growing nine to ten meters long and possibly weighing 2.5 metric tons or less.
  Since the first discovery in 1884, fossils of more than 30 individuals have been recovered, providing scientists with a more detailed knowledge of Albertosaurus anatomy than is available for most other tyrannosaurids.
context_section_description: On 11 August 1910, American paleontologist Barnum Brown discovered the remains of a large group of Albertosaurus at another quarry alongside the Red Deer River. Because of the large number of bones and the limited time available, Brown's party did not collect every specimen, but made sure to collect remains from all of the individuals that they could identify in the bonebed. Among the bones deposited in the American Museum of Natural History collections in New York City are seven sets of right metatarsals, along with two isolated toe bones that did not match any of the metatarsals in size. This indicated the presence of at least nine individuals in the quarry. Palaeontologist Philip J. Currie of the Royal Tyrrell Museum of Palaeontology rediscovered the bonebed in 1997 and resumed fieldwork at the site, which is now located inside Dry Island Buffalo Jump Provincial Park. Further excavation from 1997 to 2005 turned up the remains of 13 more individuals of various ages, including a diminutive two-year-old and a very old individual estimated at over 10 metres (33 feet) in length. None of these individuals are known from complete skeletons, and most are represented by remains in both museums. Excavations continued until 2008, when the minimum number of individuals present had been established at 12, on the basis of preserved elements that occur only once in a skeleton, and at 26 if mirrored elements were counted when differing in size due to ontogeny. A total of 1,128 Albertosaurus bones had been secured, the largest concentration of large theropod fossils known from the Cretaceous.
caption: Teeth from Dry Island and Drumheller, Royal Tyrrell Museum
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