Gorgosaurus, meaning “fierce lizard”, is a genus of tyrannosaurid theropod dinosaur from the Late Cretaceous Period (77 to 74 million years ago) that lived in what is now western North America. It has been discovered in Alberta, Canada and possibly Montana, USA. Only one type species is known, G. libratus. Gorgosaurus was first described by Lawrence Lambe in 1914. Several specimens have been discovered, the first by Charles M. Sternberg in 1913. It was also the first tyrannosaurid dinosaur to be found with a complete hand. It was discovered at Dinosaur Park Formation in Alberta. Four other complete skulls of this species were also collected along the Red Deer River in Alberta by other prospectors.
Gorgosaurus was a bipedal predator weighing more than 2200 pounds. Some adults may have weighed even more than 5400 pounds. It grew to a length of 26 to 30 feet from head to tail. Its large skull was, at most, 39 inches long. The skull was large compared to the rest of its body. Its teeth were typical of all known tyrannosaurids. Eight teeth at the front of the snout were smaller than the rest, closely packed together. It also had 26 to 30 maxillary teeth and 30 to 34 teeth in the dental battery of the lower jaw. Its head was placed on the end of an S-shaped neck. In contrast to the overly large head, its forelimbs were quite small. Forelimbs had two digits, with a third in some species, and four digit on the hind limbs. It had a long, heavy tail that served as a counterweight to the head and torso. The center of gravity was placed at the hips. Gorgosaurus spent nearly half of its life in the juvenile phase before sprouting up to near-maximum size in just a few short years.