Dino of the week: Edmontonia

An armoured dinosaurnamed for Alberta's capital has been living in the shadow of its more famous cousin.

Edmontonia belongs to a "forgotten" branch of the armoured dinosaur family tree. The tank-like critter isa nodosaurid, as opposed to the much more famous ankylosaurids.

As part of the summer-long series Backyard Dinosaurs which features a different Alberta dinosaureach week University of Alberta paleontologist Scott Persons told CBC Edmonton's Radio Active how the city's namesake dinosaur has lost the limelight to itsdistant relative.

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Ankylosaurids were armoured dinosaurs with a bony club atthe ends of their tails whichcould be used defensively againstpredators such astyrannosaurs.

"Their tail weaponry makes ankylosaurids work well as as subjects for dramatic museum murals or action figures or as characters in Saturday morning cartoons," Persons said.

"Ankylosaurids have made appearances in the last two Jurassic Park movies, but the directors have yet to cast a nodosaurid," he said.

At least the poor Edmontoniahad plenty of weaponry to defend themselves, said Persons.

Something to fight about?

Nodosaurids'tails were lined along either side with a row of triangular spikes, like "the teeth down the blade of a saw," which could be used to slash a predator.

Nearly sevenmetres long, the Edmontoniaalsohad akiller set of shoulder pads. The bony spikes over Edmontonia's shoulders grew to over a foot long, with some pointing sideways and others facingdead ahead.

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"When threatened, Edmontonia could do a lot more than just hunker down, it could charge forward and swerve at impact to sideswipe a predator," Persons said, who arguesthe beast deserves more respect.

"You'd think that, at least locally, a dinosaur named Edmontonia that was specifically adapted to shoulder-check tyrannosaurs would gain a little more fame."

But dinosaur fanscan take solace in one hypothesis about these fearsome creatures, Persons said.

Though there is no direct fossil evidence for it, the Edmontonia probably co-habitated peacefully with its famed cousins, and the evidence is in theanatomy.

Ankylosaurids have boxier heads with short snouts and round beaks, while nodosaurids have longer snouts and more pointed beaks. This suggests that the two ate different things and in a different way.

"With a short, blunt beak, ankylosaurs were probably not picky eaters and grazed on whatever they found," Persons explained.

"Nodosaurids like Edmontonia, had mouths better suited for selective feeding. They probably opted to eat the choicest, most nutritious plantsand favoured food quality over sheer quantity.

"Ankylosaurids and nodosaurids probably did not have a great deal to fight about."