Daspletosaurus was a genus of large tyrannosaurid from the U.S and Canada that lived during the Campanian Stage (Late Cretaceous). Despite being a close relative of Tyrannosaurus, it was geologically older.
Daspletosaurus was a tyrannosaur, but not largest member of the family Tyrannosauridae . It still measured 8-9 meters (26-30 feet) in length and weighed about 2.75 short tons (2.5 tons). Daspletosaurus was equipped with a massive skull that reached an impressive meter (3.3 ft) in length. These jaws were lined with about 72 teeth with oval shaped cross sections. The bones were robust and heavily built, with some fused, for example the nasal bones, for added strength. The eye sockets of Daspletosaurus were tall and oval shaped. Like other tyrannosaurs, Daspletosaurus had reduced arms to counterbalance its massive head and would have walked with a horizontal vertebrae posture with its tail held erect for balance.
Bite marks on the skulls of Daspletosaurus suggest violent confrontations took place between individual juveniles and adults. Many of the marks show signs of healing, therefore, meaning the Daspletosaurus' survived the encounter with rivals Other theropods such as Tyrannosaurus , Gorgosaurus , and Sinraptor also show signs of bite marks from the same species. There is also evidence Daspletosaurus lived in groups. In the Two Medicine Formation of Montana, 3 D. torosus were found together, an adult, an intermediate (possibly a subadult), and a juvenile. 5 hadrosaurus were also found there suggesting that the D. torosus were feeding at the time of there death, and possibly, had worked together to make a kill.
Daspletosaurus would have been an apex predator of its area, coexisting with Gorgosaurus , another Tyrannosaurid. They probably hunted different prey, to fill different ecological niches. It was one theorized that Gorgosaurus preyed on the more abundant hadrosaur and Daspletosaurus preyed on ceratopsians. However, fossils of hadrosaurs have been found in the digestive tracts of Daspletosaurus.
Species and Classification
Aside from D. torosus, at least 3 other species have been assigned to Daspletosaurus, however, many have not been formally described and may be junior synonyms. D. torosus is a member of the family Tyrannosauridae and while the similar Tarbosaurus and Tyrannosaurus are considered sister taxons, Daspletosaurus is considered a more basal relative of the two.