The Albertosaurus had two-fingered front limbs, but no one knows what they were used for.
The Albertosaurus weighed less than half of what a Tyrannosaurus weighed.
It's possible that young, fast-moving juvenile Albertosaurus pack members drove prey to the slower adults.
The Albertosaurus had long hind legs that likely enabled swift movement, especially among younger members of the species.
The Stygimoloch weighed about 170 pounds and was around 10 feet long and three feet high.