Albertosaurus
Channel: 宇宙のすべての知識 プリンシピア
Date: 11/01/2019

Albertosaurus, by Wikipedia https://en.wikipedia.org/wiki?curid=1367 / CC BY SA 3.0

Albertosaurus

Albertosaurus (; meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaurs that lived in western North America during the Late Cretaceous Period, about 70 million years ago. The type species, "A. sarcophagus", was apparently restricted in range to the modern-day Canadian province of Alberta, after which the genus is named. Scientists disagree on the content of the genus, with some recognizing "Gorgosaurus libratus" as a second species. 

As a tyrannosaurid, "Albertosaurus" was a bipedal predator with tiny, two-fingered hands and a massive head that had dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. While "Albertosaurus" was large for a theropod, it was much smaller than its larger and more famous relative "Tyrannosaurus rex", growing nine to ten meters long and possibly weighing less than 2 metric tons.

Since the first discovery in 1884, fossils of more than 30 individuals have been recovered, providing scientists with a more detailed knowledge of "Albertosaurus" anatomy than is available for most other tyrannosaurids. The discovery of 26 individuals at one site provides evidence of pack behaviour and allows studies of ontogeny and population biology, which are impossible with lesser-known dinosaurs.

"Albertosaurus" was smaller than some other tyrannosaurids, such as "Tarbosaurus" and "Tyrannosaurus". Typical "Albertosaurus" adults measured up to long, while rare individuals of great age could grow to be over long. Several independent mass estimates, obtained by different methods, suggest that an adult "Albertosaurus" weighed between 1.3 tonnes and 1.7 tonnes (1.9 tons).

"Albertosaurus" shared a similar body appearance with all other tyrannosaurids. Typically for a theropod, "Albertosaurus" was bipedal and balanced the heavy head and torso with a long tail. However, tyrannosaurid forelimbs were ext...