Temporal range: Upper Cretaceous
Albertosaurus was a relative of Tyrannosaurus. Albertosaurus was smaller than T. rex and lived a few million years earlier. Albertosaurus walked on two legs and had a large head with sharp, saw-toothed teeth. It had two-fingered hands on short arms. Its long tail provided balance and quick turning. It had powerful back legs with clawed, three-toed feet.
It was about 30 feet (9 m) long, about 11 feet (3.4 m) tall at the hips, and up to 3 tons in weight (averaging roughly 2500 kg). The lower jaw of Albertosaurus had from 14 and 16 teeth; the upper jaw had 17-19 teeth. It had one row of teeth in each jaw but had at least one replacement tooth growing up from under each tooth.
Albertosaurus was more lightly built than Tyrannosaurus, and therefore probably a faster mover in open spaces.