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Royal Ontario Museum technician Ian Morrison holds part of the jaw of the dinosaur named after him. He figured out how to fit the fragments together into a single piece. (Brian Boyle/Royal Ontario Museum)

Two new dinosaur species from Alberta, including one of the smallest adult plant-eating dinosaurs ever discovered, have been named after Canadians.

The first, which was about the size of a medium-sized dog, was named Gryphoceratops morrisoni, after Ian Morrison, a technician at the Royal Ontario Museum in Toronto, who figured out how fossil fragments from the dinosaur's jaw fit together.

That was a task that had frustrated ROM assistant curator David Evans and his colleague Michael Ryan at the Cleveland Museum of Natural History for eight years.

"It took him about an hour," Evans said in an interview Tuesday. "He is a genius at putting three-dimensional puzzles together."

The dinosaur, which lived about 83 million years ago, grew to be no more than half a metre long, or about the size of a springer spaniel, not including its tail. It belongs to a group of "horned" dinosaurs called Leptoceratopsids. They're related to Triceratops —  famous for its impressive size, horns and frill — but are smaller, with only a subtle frill and ridges over their noses and eyes in place of long, pointed horns.

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Gryphoceratops morrisoni is the smallest species of horned dinosaur ever found in North America. (Julius T. Csotonyi/Cleveland Museum of Natural History)

The other new species from the same family, Unescopceratops koppelhusae, has been named after Eva Koppelhus, a University of Alberta biologist who studies ancient plant spores and pollen that have been used to help figure out the age of other dinosaur fossils.

She is the wife of Philip Currie, the University of Alberta paleontologist who discovered the fossil at Alberta's Dinosaur Provincial Park. While she didn't have a direct role in the discovery, Evans said she has been an important mentor to many young paleontologists including himself.

The first part of the dinosaur's name is the reference to the fact that the park is a UNESCO World Heritage Site. Unescopceratops koppelhusa lived about 75 million years ago, grew to be about two metres long and weighed about 91 kilograms, making it about the size of a deer.

Both new species were identified and described from fragments of jawbones found some time ago. Fragments from the jaw of Gryphoceratops morrisoni were discovered in the Milk River rock formation in southern Alberta by Royal Ontario Museum paleontologist Levi Sternberg in 1950.

Evans rediscovered the fragments in a drawer in the museum about a decade ago and recognized them as belonging to a Leptoceratopsid dinosaur, but couldn't get much more information until Morisson pieced them together.

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Unescopceratops koppelhusa lived about 75 million years ago and was about the size of a deer. (Julius T. Csotonyi/Cleveland Museum of Natural History)

The fossil of Unescopceratops koppelhusa was discovered by Currie in 1995, and was known to be a Leptoceratopsid. It was later identified as being part of a completely new genus and species by Evans and Ryan, based on a comparison with other recently discovered species.

Evans, who co-authored the paper describing the new dinosaurs, said such small dinosaurs are usually poorly represented in the fossil record because their bones are more easily chewed apart or swallowed by predators, compared to those of larger dinosaurs. They become scattered and harder to find.

That means any discoveries of their fossil remains provide important information about dinosaur evolution. In this case, both new species are the only members of their family ever found from their time period and Gryphoceratops morrisoni is the oldest member of its family ever found.

Both new dinosaurs were described in the upcoming June issue of the journal Cretaceous Research, which was published online earlier this year.