Concept

Albertosaurinae

Résumé

Albertosaurines, or dinosaurs of the subfamily Albertosaurinae, lived in the Late Cretaceous of United States and Canada. The subfamily was first used by Philip J. Currie, Jørn H. Hurum, and Karol Sabath as a group of tyrannosaurid dinosaurs. It was originally defined as "(Albertosaurus + Gorgosaurus)", including only the two genera. The group is the sister clade to Tyrannosaurinae. In 2007, it was found that the group also contained Maleevosaurus, often synonymized with Tarbosaurus. However, this classification has not been accepted and Maleevosaurus is still considered a juvenile Tarbosaurus or Tyrannosaurus. Albertosaurines are large, lightly built tyrannosaurids. Compared to tyrannosaurines, they are more slender and have shorter, flatter skulls, shorter ilia, and proportionally longer tibiae. Albertosaurines and tyrannosaurines share arms of about equal length, with the exception of Tarbosaurus, which had short arms for its size. Albertosaurus was smaller than some other tyrannosaurids, such as Tarbosaurus and Tyrannosaurus. Typical adults of Albertosaurus and Gorgosaurus measured up to long, while rare individuals of Albertosaurus could grow to over in length. Several independent mass estimates, obtained by different methods, suggest that an adult Albertosaurus weighed between and . Gorgosaurus estimates are higher, around , although greater estimates exist of about . All tyrannosaurids, including Albertosaurus, shared a similar body appearance. Typical for a theropod, Albertosaurus was bipedal and balanced its heavy head and torso with a long tail. However, tyrannosaurid arms were extremely small for their body size and retained only two digits. The legs were long and ended in a four-toed foot. The first digit, called the hallux, was short and only the other three contacted the ground, with the third (middle) digit being longer than the rest. Albertosaurus may have been able to reach walking speeds of 14−21 kilometres per hour (8−13 miles per hour). At least for the younger individuals, a high running speed is plausible.

Source officielle

https://en.wikipedia.org/wiki/Albertosaurinae

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