Late Jurassic - 150 Mya
Midwest USA: Colorado, Montana, New Mexico, Oklahoma, South Dakota, Utah, Wyoming; also Europe (Portugal) and Africa
Length: 12 meters (39 feet)
Height: 5 meters (16 feet)
Weight: 1,700 kg (3,800 lb)
Studies of Allosaurus hindlimbs indicate that juveniles had a longer leg length than sub-adults or adults. This fact would indicate that locomotion was also different.
As a young animal Allosaurus may have had more multi-directional loads and stresses on the hindlimb which is associated with agile running, not in a straight forward direction only as is indicated in adults. This ability to change direction quickly meant that the feeding strategy of a juvenile was far different than an adult. As a juvenile, Allosaurus may have been able to pursue small vertebrate prey but switched to being a more ambush-type predator as it grew larger.