A. arctunguis
?A. libratus
A. sarcophagus (type)

Albertosaurus (al-BURR-to-SORE-us) is the genus name for several species of tyrannosaurids that looked similar to Tyrannosaurus rex, but were somewhat smaller. Albertosaurus also tended to be less massive than T. rex, as well as its contemporary Daspletosaurus (also a tyrannosaurid of similar length).

The co-existence of these two animals have lead to the suggestion that they were specialized for killing different kinds of prey: Albertosaurus may have went after fleeter prey, like duck-billed dinosaurs and ornithomimids, while Daspletosaurus tackled heavier horned dinosaurs.

Like Tyrannosaurus, Albertosaurus had small arms and a huge head with recurved serrated teeth. These teeth however, are more strongly curved than those of Tyrannosaurus. Unlike Tyrannosaurus, who underwent much evolutionary change, all discovered specimens of Albertosaurus suggest that they didn't evolve much in over 10 million years, except for a trend towards a more slender or gracile form.

Albertosaurus is named after the Canadian province of Alberta.

Species

Albertosaurus arctunguis (Parks, 1928).

• Skull length : up to 1 m.
• Total length : 8 m.
• Hip height  : 2.5 m.
• Weight  : 2 tonnes

Albertosaurus libratus (Lambe, 1914) is today usually referred to as Gorgosaurus libratus. This change of genera is advocated by many paleontologists, who claim that there are enough differences between A. libratus and the other Albertosaurus species to resurrect the older genus name of Gorgosaurus.

• Skull length : up to 1 m.
• Total length : 8.6 m.
• Hip height  : 2.8 m
• Weight  : 2.5 tonnes

Albertosaurus sarcophagus (Osborn, 1905), the type species of the genera.