Tumbler Ridge fossil find rewrites history of an ancient fish

Trent Ernst, Editor

Sheena Walkley, back in 2006. She discovered the Colecanth fossil while exploring near Wapiti lake.

A local fossil continues to make waves in the scientific community, years after it was discovered.

It was the summer of 2006, and Sheena Walkley was out with her family, along with the Helms and the Byren family from Oxford, UK, looking for fossils in the Wapiti Lake area.

Walkley, who was 13 at the time, discovered a beautiful fish fossil just laying on the ground. “Everyone kept finding stuff,” says Walkley. “It’s like a gold mine there, with all these fossils just lying on the side of the hill.”

Walkley called the adults over to take a look at the fossil. The stone was broken in half, but a moment’s casting about by Charles Helm found the other half. “We called it our book fossil,” says Walkley. “It was broken in two halves and laying there just like an open book. Everyone was like ‘holy smoke, look at that size of that fish; that’s a keeper.’”

Walkley remember that the excitement of finding the fossil was blunted somewhat by having to carry all the fossils out on their backs. “I didn’t have to carry that one out. It was too big, but I carried out a bunch of teeth and smaller stuff like that.”

While they weren’t sure of what the fossil was at the time, Charles Helm suggested that it might be a coelacanth. Coelacanths are an ancient group of fishes once thought to be long extinct. However, they are one of the most famous of the prehistoric fish, because in 1938 one of their modern relatives was caught off the coast of South Africa.

Now coelacanths are making another  splash and it’s all thanks to this fossil.

Andrew Wendruff from the University of Alberta, looked at that fossil and noticed that is was so dramatically different from previous finds, it shattered the theory that coelacanths were evolutionarily stagnant in that their body shape and life-style changed little since the origin of the group.

Wendruff says the one-metre-long, forked tailed coelacanth was an ‘off-shoot’ lineage that lived 240 million years ago. It falls between the earliest coelacanth fossils of 410 million years ago and the latest fossils dated about 75 million years ago, near the end of the age of dinosaurs.

“Our coelacanth had a forked tail, indicating it was a fast-moving, aggressive predator, which is very different from the shape and movement of all other coelacanths in the fossil record,” said Wendruff.

Coelacanth fossil.

Wendruff’s research co-author, U of A Professor Emeritus Mark Wilson, describes typical coelacanths as having chunky bodies, fins of varying size and broad, flexible tails. “These fish were slow moving and probably lay in wait for their prey,” said Wilson.

Wendruff’s coelacanth is named Rebellatrix, which means rebel coelacanth. The researchers say Rebellatrix came along after the end-Permian mass extinction 250 million years ago, an event so lethal it wiped out 90 percent of marine life. Rebellatrix filled a previously unoccupied predator niche, but it didn’t fare well.

“Rebellatrix was likely a spectacular failure in the evolution of cruising predation,” said Wendruff. “Clearly some other fish groups with forked-tails must have outperformed this coelacanth as it does not appear later in the fossil record.”

For Walkley, the news comes as a blast from the past. “I was actually shocked that it’s coming up now. It was how long ago that trip happened?”
The research by Wendruff and Wilson was published May 2, as the cover article in the Journal of Vertebrate Paleontology.