70 million years ago, give or take a few

Well, it wasn't on a Tuesday, but Dick and I, with our dog Lindy, recently visited Dinosaur Provincial Park near the small town of Patricia, Alberta.

Like other parts of Alberta that consist of similar territory, Dinosaur Provincial Park's unique terrain is known locally as "badlands."

In the third and fourth photos here, the Red Deer River can be seen running through the park, eventually to join up with the South Saskatchewan River, which flows past our town and through the city of Medicine Hat.

Here, many fossils have been found of a dinosaur with long legs and short arms, which once roamed this area. 

It is called Albertosaurus (meaning "Alberta lizard") is a genus of tyrannosaurid theropod dinosaur 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 with dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. Although relatively large for a theropod, Albertosaurus was much smaller than its more famous relative Tyrannosaurus, probably weighing less than 2 metric tons.

Photos by Kay Davies and Richard Schear

Since the first discovery in 1884, fossils of more than thirty 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. 

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Our World Tuesday