02/20/2014 05:01 EST | Updated 04/22/2014 05:59 EDT

Massive, Rare Dinosaur Skull Found In Drumheller (PHOTO)

CALGARY - A rare dinosaur skull unveiled by University of Calgary paleontologists Thursday was literally hiding in plain sight.

Even with Prof. Darla Zelenitsky pointing out the eye socket of the massive pachyrhinosaur's skull, it still looked like just a giant chunk of rock.

And, with it being found inside the town limits of Drumheller — billed as the dinosaur capital of the world — it probably had hundreds of prehistoric enthusiasts traipsing over it for decades before anyone noticed.

"It appeared to me as being a fairly well-trampled area, and my research assistant had pointed out what looked like a rock with a bumpy surface. We eventually started to excavate and realized it was potentially part of a horned-dinosaur skull," said Zelenitsky.

"After several days of excavating we realized it was a good portion of one of these pachyrhinosaur dinosaur skulls, so it was really quite exciting."

Pachyrhinosaurs were four-legged herbivores that lived about 72 million years ago in what is now Alberta and Alaska. They could grow to over six metres in length and weighed four tonnes. Their heads were adorned with big bony bumps and horns, and large frills extended over the back of their necks.

The head features were probably used for mating competition or combat. Zelenitsky said the dinosaur is likely to have had few enemies.

She said the specimen found in Drumheller appears to be that of a mature pachyrhinosaur — and that's rare.

"From the Drumheller area there's very few pachyrhinosaur skulls that have been collected. There was part of one that was collected over 50 years ago, so this is the first one in 50 years and we've got a good portion — probably 75 to 80 per cent of it."

Zelenitsky said there may have been other pachyrhinosaur specimens found over the years, but it is impossible to identify without the skull.

The recovery team plans to be back at the site this spring with the hope there will be more of the specimen buried in the ground.

Zelenitsky said five to six tonnes of rock needed to be removed over 10 days to extract the skull. The past several months were spent preparing it in the laboratory to carefully remove the rock encasing the bone.

"So far, the upper part of the skull has been exposed and the skull will be flipped over to prepare the lower part, including the jaws," said Zelenitsky. "There are still many months of work necessary in order to clean the entire skull.

"Our initial goal will be to determine if this specimen represents a new species."

Following that, the specimen will be measured and scanned to help document how the skull of pachyrhinosaurs changed during growth, particularly in the later stages of life.

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