Hailed as a first in dinosaur science, a Canadian paleontol-ogist has used fossilized skin rather than bone to differentiate between two species of had-rosaurs - also known as duck-billed dinosaurs - from Alberta and Mongolia.

The finding by University of Alberta researcher Phil Bell, detailed in the latest issue of the journal PLoS ONE, offers researchers a potential new way to identify dinosaurs from a wide range of Jurassic and Cretaceous dig sites around the world.

"Previously, dinosaur paleontologists relied only on bones to tell between species," states a summary of Bell's discovery issued by Alberta's Pipestone Creek Dinosaur Initiative. "However, the new study demonstrates another option."

Bell, who also is heading a dinosaur research project at the Pipestone Creek bonebed near Grand Prairie, Alta., com-pared Mongolian hadrosaur fossils that preserved "spectacular skin impressions" with similarly detailed hadrosaur fossils excavated in southern Alberta about 100 years ago. Previous analysis of the preserved bones had determined that while the Mongolian and Canadian specimens were both duck-billed dinosaurs and shared many characteristics, they belonged to different species of hadrosaur: Saurolo-phus angustirostris from Mongolia and Saurolophus osborni from Canada.

Bell, however, was able to reach the same conclusion - that the dinosaurs belonged to separate species - by isolating distinctive scale patterns on each animal's skin, impressions of which were well preserved in rock.

"Differences are most spectacular in the tail," the published study states, "where S. angu-stirostris is differentiated by the presence of vertical bands of morphologically distinct scales" and other variations from the Alberta specimen. "It changes the way we are approaching paleontology," Bell said. "Back in the day, it was, 'find as many bones as you can and name as many species as you can.' Now, as the field has matured, people are asking different questions, recognizing these animals as living entities rather than curios in a museum."

The ability to classify a long-extinct species based on skin impressions, the study states, could allow paleontologists to make use of techniques employed by biologists to distinguish living species and subspecies by comparing skin, feather and fur traits.

Despite the "relatively rich fossil record" of hadrosaur skin and the fact well-preserved scales and feathers exist for "most major groups" of dinosaurs, "few attempts have been made to characterize species based on these structures," the PLoS ONE article states.