There has been many tyrannosauroid dinosaurs found in the northernmost portions of North America like Nanuqsaurus and Gorgosaurus; however, the largest and bulkiest of these animals is undoubtedly Daspletosaurus. Its name means, “Frightful Lizard”, and lived during the Campanian stage of the Cretaceous period, approximately 77 to 74 Million years ago. Daspletosaurus is superficially similar to most advanced Tyrannosaurs, but definitely has enough differences to make it its own genus and species and also shows characteristics of a terrifying predator.
Charles Mortram Sternberg discovered the initial fossil material in 1921 near the town of Steveville, Alberta. The material he found consisted of; the skull, shoulder, a forelimb, pelvis, a femur, all of the vertebrae from the neck, torso and hip, and the first eleven tail vertebrae. Sternberg falsely identified his discovery as a member of the genus; Gorgosaurus. However, the animal became identified as a separate genus by paleontologist, Dale Russell, in 1970; named as Daspletosaurus torosus. Russell named the species D. torosus, which means “Brawny”, as the animal’s advanced bulkiness is seen mostly in later Tyrannosaurs. Many fossils of this animal have since been found like; A specimen found by famed paleontologist, barnum brown in 1913, and many other specimens from the Dinosaur Provincial Park Formation in Canada. One of the most interesting Daspletosaurus fossils, and also the most recent (2001), consists of a partial skeleton and shows preservation of a juvenile hadrosaur within its chest cavity (Gut), this gives scientists a big clue as to what Daspletosaurus was eating.
Daspletosaurus fossils have been found in the canadian Oldman and Dinosaur Park formations as well as the Two Medicine Formation of Montana. The environment in which the animal would have lived would also have housed many other animals including; Gorgosaurus, Brachylophosaurus, Coronosaurus, Sauronitholestes, etc. Daspletosaurus lived at the same time and place as the smaller and more gracile predator, Gorgosaurus. This presents a problem; how can two ‘top’ predators share similar niches in the same time and space, and the short answer is: they cannot. The bodies of these two predators are shaped rather differently to one another. Gorgosaurus was slim and gracile with a similarly slender skull (weaker than Daspletosaurus), and Daspletosaurus had a large bulky skull like the later Tyrannosaurus, with a body to match the proportions. The prevailing theory states that these two theropods would likely have preyed upon different animals and lived in two separate regions; solving the niche problem. Fossils of Daspletosaurus are far rarer in the places in which Gorgosaurus fossils are more common. As has been previously illuminated, there is a fossil of Daspletosaurus that has preserved the remains of the animal’s last meal, in this case a young hadrosaur. This would seem to contradict the theory of niche differentiation (Gorgosaurus hunts faster less armored prey, and Daspletosaurus hunts bigger, slower armed prey). This issue has yet to be settled and more research is needed on the subject for further conclusions to be found.
Daspletosaurus, as previously stated, shows more characteristics of later bulkier Tyrannosaurs than the more primitive forms. It has been placed, cladistically, as being more advanced than the Albertosaurini subgroup (Albertosaurus and Gorgosaurus) and more primitive than the rest of the group (Teratophoneus, Tyrannosaurus, etc.). Which just goes to show, Tyrannosauridae was a very diverse group of animals.