3 minute read
Whaleontology
The atlas (first neck vertebra) of a squalodelphinid, an ancient relative of modern river dolphins, from the Sooke Formation of Vancouver Island. Two vertebrae (backbones) of an early aetiocetid whale found in the Sooke Formation of Vancouver Island.
By Dr. Victoria Arbour Curator of Palaeontology
AT THE ROYAL BC MUSEUM
Today, the waters around the shores of Vancouver Island are home to many species of whales, like the iconic Southern Resident orcas or the giant filter-feeding grey whales and humpbacks. But did you know that whales also swam in these waters 25 million years ago?
Over the years, many interesting bits and pieces of marine mammals have been collected from places like Muir Creek Beach, Kirby Creek and Sombrio Beach. But besides the partial skeleton of an unusual animal called a desmostylian—sometimes referred to as a sea hippo—none of these fossils have been studied in detail. University of Victoria undergraduate science student Elizabeth Rohlicek worked with me over the last year to dig deep into the museum’s collection of whale fossils from southern Vancouver Island.
Whale fossils on Vancouver Island come from a set of rocks that geologists call the Carmanah Group, and most of these were formed during the Oligocene Epoch, about 34 to 23 million years ago. Carmanah Group rocks often form cliffs full of light-coloured fossil shells, but every so often, someone stumbles across a dark brown piece of fossil bone. Our collection includes many ribs and rib fragments, vertebrae (backbones), small pieces of skulls and jaws, and even a scapula (a shoulder blade). What kinds of whales did these bones come from?
Vertebra from an early fossil whale, possibly a basilosaurid, from Vancouver Island. Pieces of the skull of an aetiocetid, an early fossil baleen whale, found on Vancouver Island in the 25-million-year-old Sooke Formation.
Elizabeth Rohlicek holding a vertebra (backbone) of an early aetiocetid whale found in the Sooke Formation of Vancouver Island.
The Oligocene is an important time period for palaeontologists interested in the evolution of whales. Although the ancestors of whales walked on land on four legs, by the Oligocene they had fully adapted to life in the water, losing their hind legs and evolving powerful tails with flukes. Today there are two major groups of whales: odontocetes, or toothed whales, who kept the sharp teeth of their ancestors and who hunt using echolocation, and mysticetes, or baleen whales, who lost their teeth and became filter-feeders. The Oligocene is when the ancestors of today’s mysticetes were beginning to lose their teeth, and when the ancestors of today’s odontocetes were evolving the ability to echolocate.
Elizabeth’s work has revealed some surprising things about the diversity of British Columbia’s ancient whales. At least three different types lived in this area at the time, but none would have looked much like the whales alive today. Skull fragments and some small vertebrae belonged to an aetiocetid mysticete, which had both baleen and teeth, and was only about six metres long. A single neck bone could only have come from a squalodelphinid odontocete, an extinct member of the larger family that today includes the Ganges and Indus river dolphins. And a single huge vertebra probably came from a basilosaurid, an archaic type of whale that was not closely related to any of today’s whales and which had a long, serpentine body.
Our work on these fossils is still ongoing, and there are almost certainly more ancient whale fossils out there waiting to be spotted by the right person at the right time! Fossils are protected in British Columbia and are managed under the Fossil Management Framework, so please contact the museum if you think you have found something interesting. We’d love to see what you find!
LEARN MORE
Learning Portal: Elizabeth Rohlicek Studies Whale Fossils
