Albertosaurus was first discovered in 1884 by Joseph B. Tyrrell in the Horseshoe Canyon, of Alberta, Canada. At this point, it was classified as being part of a separate species. The Albertosaurus appears similar to Tyrannosaurids of its time including its sister fossil the Gorgosaurus. Henry Fairfield Osborn finally named it the Albertosaurus in 1905.
Albertosaurus looked like a miniature version of the Tyrannosaurus. Like others of its kind, it was a bipedal predator, balancing its massive head and s-shaped neck with a long and thick tail. Its jaw held over 60 banana-shaped teeth. It also had short crests above the eyes, which at one point may have been colored and used for display. Its arms, like the Tyrannosaurus, were uselessly small with two clawed fingers on each arm.