The most diverse, amber-preserved, fossilized feather collection ever found – unearthed in the prairies of southeastern Alberta – is shedding new insight into the evolution of dinosaur and bird feathers.
The fossils were recovered from pits once used to store tailings from coal mining near Grassy Lake, a hamlet about an hour's drive east of Lethbridge.
The region is a treasure trove of remnants from the dinosaur age. A team of scientists from the University of Alberta believes the feathers, 11 in total, are from the Late Cretaceous period, which spanned 99 million to 66 million years ago.
In the world of fossil hunting, a specimen encased in amber is a precious and rare find. Tough and translucent, amber offers unparalleled preservation and an extraordinarily detailed window to the past.
Veteran paleontologist Brian Chatterton, co-author of a research paper on the Alberta feathers published Thursday in the journal Science, said these fossilized feathers are significant because they offer the most comprehensive snapshot of the structure, colour and shape of early feathers.
"It's the first discovery of three-dimensional dinosaur feathers," added Dr. Chatterton, professor emeritus at the University of Alberta. "The only previous ones occur in China and they're all compression fossils, basically carbonized films on shale."
What is also remarkable is the range of feathers found. The work of combing through about 4,000 tiny pieces of amber, which were no larger than a centimetre and were collected over the past decade by scientists and amateur fossil hunters, fell largely to paleontologist Ryan McKellar. With the aid of a dissecting microscope, it took three weeks to screen the entire sample for feathers.
The Alberta amber collection represents four distinct stages of feather evolution, including primitive single-filament protofeathers – fuzz, really, which scientists believe belonged to non-flying dinosaurs such as mighty tyrannosaurids – and complex structures with side branches that resemble feathers of modern diving birds.
The fossils also reveal that feathers from Late Cretaceous were not uniform in colour: Some were light, some dark. In the case of the Chinese shale feather fossils, colour couldn't be seen, Dr. Chatterton said.
Research into ancient dinosaur and bird feathers is still at a nascent stage but has been growing rapidly in the past decade, said Mark Norell, chairman of the paleontology division at the American Museum of Natural History in New York.
He estimates 95 per cent of the world's fossilized feathers have been found in Asia. Evidence from an earlier age in China demonstrates some dinosaurs were feathered, the fuzz likely serving as insulation.
The Alberta discovery reinforces the notion that modern feather adaptation appeared before non-flying dinosaurs were extinct, Dr. Norell said. The prevailing theory among scientists is that birds descended from dinosaurs.
Evolution, Dr. Norell added, doesn't follow a linear pattern. The fossilized feathers from the prairies illustrate this point.
"Evolution is more of a branching system," he said. "Even up to the very terminal stages of this non-dinosaur time, we still have these very primitive sorts of feathers that are occurring within the same ecosystem with … very highly specialized feathers just like you would see in bird life today."
Discoveries of dinosaur feathers have helped reshape the public's perception of the extinct creatures. Gone are the days when dinosaur skin was thought of as solely scaly.
"You can kind of track where the science is going by just looking at contemporary culture," Dr. Norell said. "If you look at the original Jurassic Park film, all the dinosaurs looked like crocodiles. And today, you look at the most recent incarnations of them, and lots of them are fluffy."