Albertosaurus, Osborn, 1905

Paul, G. S., 1988, Predatory Dinosaurs of the World, Predatory Dinosaurs of the World, New York: Touchstone Books, pp. 323-349 : 327-328

GENUS ALBERTOSAURUS Osborn, 1905

synonyms— Alectrosaurus ? Deinodon , Gorgosaurus

For a long time, Albertosaurus was better known as Gorgosaurus , but in 1970 Dale Russell decided that the first name has priority. This may not have been the best thing. The problem is that the type skull of Albertosaurus , which is that ofA. sarcophagus , is so badly preserved that much work will have to be done on it and other specimens in order to determine exactly what the genus encompasses. Albertosaurus appears to be restricted to North America, with the apparent exception of the Mongolian A. olseni . Perhaps it did not favor the drier habitats of Asia. Why this would be so is not obvious since big predators are often catholic in habitat choice.

This genus is generally less advanced than Tyrannosaurus in having a lower, longer-snouted, shallower-jawed, lighter skull with less interbracing in the skull roof. The adult’s teeth are smaller, and point more backward than in Tyrannosaurus . There are fewer differences in the skeleton, though Albertosaurus never got larger than a white rhino. In a sense the species of Albertosaurus can be regarded as tyrannosaurian “foxes” relative to the more robust Tyrannosaurus “wolves and jackals.” Russell made the pertinent observation that the slender albertosaurs may have tended to hunt the more easily dispatched duckbills, leaving the formidable horned dinosaurs for stouter Tyrannosaurus .

The members of this genus are very similar, except for A. lancensis , which is more Tyrannosaurus-like than the others, and at the least needs its own subgenus. A. libratus , A. arctunguis and A. megagracilis appear to form an increasingly advanced, shorter-armed, and gracile lineage.