Palaeontologist Michael Ryan holds up the fossil skull of the newly discovered Albertaceratops

Credit: Chad Kerychuk, Digital Dream Machine

Related articles

• Huge duck-billed dinosaur unearthed in Utah
• Large flock of parrot-like dinosaurs uncovered
• Velociraptor relative was sloth-like herbivore
• Australia's largest ever dinosaur unveiled
• Dino diversity had a long pedigree

SYDNEY: An ancestor of triceratops, with metre-long horns over its eyebrows, has been unearthed in Canada.

The find provides new insights into the evolution of the iconic family of vegetarian dinosaurs. Named Albertaceratops nesmoi, it is only the second horned dinosaur to have been discovered in Canada since the 1950s. The 78-million year old species was six metres in length and would have weighed as much as a pick-up truck.

The dinosaur's horns - thick as a human arm - are like those of triceratops, which appeared 10 million years later, shortly before the demise of the dinosaurs at the end of the Cretaceous period.

"Unquestionably, it's an important find," said palaeontologist Peter Dodson of the University of Pennsylvania in Philadelphia, USA. "It was sort of the grandfather or great-uncle of the really diverse horned dinosaurs that came after it."

Albertaceratops belonged to the Centrosaurinae, one of two subfamilies of the horned dinosaur family Ceratopsidae. Plant-eating dinosaurs in this subfamily usually sport short horns over their eyes, a long horn protruding from the nose and spikes or hooks on the bony frill that projects from the back of their skulls.

The new fossil has a unique "banana-shaped" bump in place of the usual nasal horn and two large hooks that curl forwards from its frill.

Experts believe the creature's horns might have been used either as a mating display tool or to joust with rivals - much like deer's antlers today. But they could also have provided a formidable defence against a massive predatory tyrannosaur called Daspletosaurus, known to have prowled Cretaceous-period Canada.

Michael Ryan, a vertebrate palaeontologist with the Cleveland Museum of Natural History in Ohio, first discovered the fossil six years ago near Maynberries in southern Alberta, Canada. He detailed the find in the current edition of Journal of Paleontology.

"My research team was stunned when we uncovered the skull and saw these long brow horns attached to a centrosaurine frill," said Ryan. "We knew that we had something special that [nobody] had ever seen before."

Alberta is home to some of the world's richest sources of dinosaur fossils. Though it has often been overlooked due to its remoteness, "The most southern part of Alberta has a tremendous potential for discovering new dinosaurs," said dinosaur expert David Evans, at the Royal Ontario Museum in Toronto, Canada.

The oldest known horned dinosaur in North America is called Zuniceratops. It lived 12 million years before Albertaceratops, and also had large horns.

That makes the newly found creature an intermediate between older forms with large horns and later small-horned relatives, said palaeontologist Jim Kirkland with the Utah Geological Survey in Salt Lake City. Kirkland, who identified Zuniceratops in New Mexico in 1998, said it was only a matter of time till a more transitional form turned up.

Ryan named the new dinosaur Albertaceratops nesmoi, after the region and in honour of Cecil Nesmo, a local rancher and long time supporter of fossil hunters.

More information:

Cleveland Museum of Natural History

Ryan's paper in the Journal of Palaeontology

More on dinosaur research in southern Alberta