Dating tyrannosaurus

-əs; meaning "frightful lizard") was a genus of tyrannosaurid dinosaur that lived in western North America between about 77 and 74 million years ago, during the Late Cretaceous Period. (Daspletosaurus sp.) Daspletosaurus is closely related to the much larger and more recent tyrannosaurid Tyrannosaurus rex.

torosus, have been found in Alberta, while fossils of the later second species, D. A possible third species, also from Alberta, awaits formal identification.

It walked on its two thick hindlimbs, which ended in four-toed feet, although the first digit (the hallux) did not contact the ground.

In contrast, the forelimbs were extremely small and bore only two digits, although Daspletosaurus had the longest forelimbs in proportion to body size of any tyrannosaurid.

Large fenestrae (openings) in the skull reduced its weight.

(2005); the authors stated that this fossil material likely represents then-unnamed species mentioned by Horner et al.It was discovered in 1921 near Steveville, Alberta, by Charles Mortram Sternberg, who thought it was a new species of Gorgosaurus.It was not until 1970 that the specimen was fully described by Dale Russell, who made it the type of a new genus, Daspletosaurus, from the Greek δασπλής (dasples, stem and connective vowel resulting in daspleto~) ("frightful") and σαυρος/sauros ("lizard").As an apex predator, Daspletosaurus was at the top of the food chain, probably preying on large dinosaurs like the ceratopsid Centrosaurus and the hadrosaur Hypacrosaurus.In some areas, Daspletosaurus coexisted with another tyrannosaurid, Gorgosaurus, though there is some evidence of niche differentiation between the two.Unlike its other teeth, those in the premaxilla at the end of the upper jaw had a D-shaped cross section, an example of heterodonty always seen in tyrannosaurids.Unique skull features included the rough outer surface of the maxilla (upper jaw bone) and the pronounced crests around the eyes on the lacrimal, postorbital, and jugal bones.Another partial skeleton was reported from the Upper Two Medicine in 2001, preserving the remains of a juvenile hadrosaur in its abdominal cavity.This specimen was assigned to Daspletosaurus but not to any particular species.While Daspletosaurus fossils are rarer than other tyrannosaurids', the available specimens allow some analysis of the biology of these animals, including social behavior, diet and life history.The bones were heavily constructed and some, including the nasal bones on top of the snout, were fused for strength.

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