The first observation that fossils are preserved in rocks in Canada was not made in the settled eastern areas by a scholar or educated naturalist. It was made in the remote Athabasca country by an observant apprentice surveyor with a rudimentary education

In 1791 the Hudson's Bay Company sent their surveyor Philip Turnor inland from York Factory to find a route into the fur-rich Athabasca country. He was assisted by the 21 year old Peter Fidler who proved himself a perceptive observer and recorder of natural history phenomena. At the headwaters of the Churchill River drainage, the small party struggled across the long difficult Methy Portage to reach Clearwater River, part of the Athabasca drainage. This river winds though a narrow outcrop belt of limestones and shales. As they tracked their canoes around one of the numerous rapids, Fidler spotted some peculiar petrified shells. His journal entry reads, "Several curious kinds of shells, some in the middle of solid stone and several in bare earth, the exact figure remaining and some appeared as if they had been petrified to a solid stone, such as cockles, muscles and other kinds of shells". This brief note appears to be the first recorded observation of fossils occurring in rocks anywhere in Canada.

The Molly Malone identification of "cockles and muscles" can safely be taken to mean generic shellfish -- and probably brachiopods, not clams. The limestones and shales exposed along the Clearwater River are now assigned to the Waterways Formation which contains some of the best preserved and most diverse early Late Devonian (Frasnian) fossil assemblages in North America. Brachiopods are particularly common -- some thin and wafer-like, but most inflated with characteristic ribs and nodes. Atrypids are the most common. These are fat, walnut-sized brachiopods with fine, tube-like ribs and lacking a discernable hinge line. Also common are stretched spiriferids with broad radial ribs and a wide straight hingeline. Domal stromatoporoids are present, as are solitary and colonial rugose corals.

Most of the marine organisms found in the Waterways Formation belong to groups that perished in a mass extinction near the middle of the Upper Devonian (375 Ma). This extinction was highly selective. With few exceptions, the animals that perished all lived in shallow marine waters. Reefs were wiped out, along with the reef-building stromatoporoids and rugose corals. Four major brachiopod groups became extinct; including the atrypids which were extremely common in earlier Devonian rocks.