PORTLAND, Ore. — Pacific Northwest nightmares are getting a revision. The saber-toothed salmon that once swam in the region may have been less saber-toothed cat and more tusky warthog.
Sharp front teeth gave the saber-toothed nickname to the extinct Oncorhynchus rastrosus fish. But rather than pointing downward like fangs, these teeth now appear to have stuck out to the sides a bit like warthog tusks, Kerin Claeson of the Philadelphia College of Osteopathic Medicine reported January 4 at the Society for Integrative and Comparative Biology annual meeting.
The monster of a salmon, reaching 2 meters or more in length and weighing more than 450 kilograms, had teeth about the length of the end segment of her thumb, Claeson said. Two fossils at least 5 million years old from central Oregon for the first time show the teeth still attached to bones from the mouth — and pointing out sideways.
No teeth except for the sabers, or tusks, have shown up in the fossils. The fish may not have had other teeth, Claeson said. The fossils do have an abundance of bones that could have held structures that raked edible tidbits off gills. So the big fish may have fed more by filtering the water than by biting prey. Or, Claeson said, the fish, like salmon today, may have had more teeth but resorbed most of them during their struggle upstream to breed.
The salmon might have used their teeth as defensive or offensive weapons, she said. Or perhaps the teeth were tools. The big teeth might have helped salmon engineer the stream bottom to shape nests for spawning.
Unexpected as the idea of sideways teeth is, fish have evolved some surprising forms, says Tetsuto Miyashita of the University of Alberta in Canada, who was in Claeson’s audience. “There’s nothing that fish can’t do,” he says.