Fossil Field Trip to Sooke

The upper Oligocene Sooke Formation that outcrops on southwestern Vancouver Island, British Columbia is a wonderful place to collect and especially good for families. As well as amazing west coast scenery, the beach site outcrop has a lovely soft matrix with well-preserved fossil molluscs, often with the shell material preserved (Clark and Arnold, 1923). While the site has been known since the 1890s, my first trip here was in the early 1990s as part of a Vancouver Paleontological Society (VanPS) fossil field trip.

By the Oligocene ocean temperatures had cooled to near modern levels and the taxa preserved here as fossils bear a strong resemblance to those found living beneath the Strait of Juan de Fuca today. Gastropods, bivalves, echinoids, coral, chitin and limpets are common-ish — and on rare occasions, fossil marine mammals, cetacean and bird bones are discovered.

Back in 2015, a family found the fossilized bones from a 25-million-year-old wing-propelled flightless diving bird while out strolling the shoreline near Sooke. Not knowing what they'd found but recognizing it as significant, the bones were brought to the Royal British Columbia Museum to identify.

The bones found their way into the hands of Gary Kaiser. Kaiser worked as a biologist for Environment Canada and the Nature Conservatory of Canada. After retirement, he turned his eye from our extant avian friends to their fossil lineage. The thing about passion is it never retires. Gary is now a research associate with the Royal British Columbia Museum, published author and continues his research on birds and their paleontological past.

Kaiser identified the well-preserved coracoid bones as the first example from Canada of a Plotopteridae, an extinct family that lived in the North Pacific from the late Eocene to the early Miocene. In honour of our First Nations communities who settled the Sooke area, Kaiser named the new genus and species Stemec suntokum. Avian fossils from the Sooke Formation are rare. We are especially lucky that the bird bone was fossilized at all. These are delicate bones and tasty. Scavengers often get to them well before they have a chance and the right conditions to fossilize.

Doubly lucky is that the find was of a coracoid, a bone from the shoulder that provides information on how this bird moved and dove through the water similar to a penguin. It's the wee bit that flexes as the bird moves his wing up and down.

Picture a penguin doing a little waddle and flapping their flipper-like wings getting ready to hop near and dive into the water. Now imagine them expertly porpoising — gracefully jumping out of the sea and zigzagging through the ocean to avoid predators. It is likely that the Sooke find did some if not all of these activities.