This giant, prehistoric fanged salmon is even more bizarre than scientists thought

EUGENE, Ore. — In the rivers of the ancient Pacific Northwest, a colossal salmon once swam – one that dwarfed even the largest of today’s prized catches. For decades, this extinct giant has captured imaginations as the “Sabertooth Salmon,” conjuring images of a fish with fearsome downward-pointing fangs. But a study published in PLOS ONE reveals that we’ve been telling fish tales about this prehistoric marvel all along.

Meet Oncorhynchus rastrosus, a salmon that grew to an astonishing 2.7 meters (8.9 feet) in length – nearly three times the size of the largest modern salmon. When first described in the 1970s, paleontologists found massive, isolated teeth unlike anything seen in living salmon. Without a complete skull to work from, they logically assumed these teeth pointed backward into the mouth like fangs. This led to the creature’s popular nickname and even its original scientific name, which translates roughly to “rake-toothed smilodon-fish.”

Now, thanks to remarkably well-preserved new fossils and advanced imaging techniques, researchers have discovered that we’ve had it all wrong. Those imposing teeth weren’t downward-facing fangs at all but rather sideways-pointing spikes!

“The teeth projected laterally like tusks, not ventrally like sabers or fangs,” the study authors explain in the report.

This radical reorientation of O. rastrosus’s most distinctive feature has scientists rethinking everything about how this fish lived and why it evolved such bizarre anatomy.

The newly analyzed fossils reveal a salmon with a broad, powerful head adorned with two massive, tusk-like teeth jutting out to the sides. Picture a salmon crossed with a warthog, and you’ll get the idea. This discovery prompted the researchers to suggest a new nickname: the “Spike-Toothed Salmon.”

“We have known for decades that these extinct salmon from Central Oregon were the largest to ever live. Discoveries like ours show they probably weren’t gentle giants,” says lead author Kerin Claeson, a professor of anatomy at Philadelphia College of Osteopathic Medicine, in a statement. “These massive spikes at the tip of their snouts would have been useful to defend against predators, compete against other salmon, and ultimately build the nests where they would incubate their eggs.”

So, why would a salmon evolve such strange headgear? The study’s authors propose several intriguing possibilities:

• Defense: Like the tusks of a warthog, the spikes may have deterred predators. Even large carnivores might think twice before trying to swallow a fish with dagger-like protrusions.
• Competition: Many animals use impressive ornaments or weapons to compete for mates. The researchers suggest the spikes may have been used in fighting, either against other spike-toothed salmon or as a defense against predators.
• Tools: Modern salmon use their tails to dig nests in riverbeds for their eggs. The researchers speculate that O. rastrosus might have used its spikes as additional digging tools to create even larger nests.

The study also sheds light on other aspects of this prehistoric giant’s life. Like modern salmon, O. rastrosus was anadromous, meaning it was born in freshwater, migrated to the ocean to grow, and then returned to rivers to spawn. Its enormous size suggests it spent significant time feeding in the productive waters of the ancient Pacific.

Intriguingly, the Spike-Toothed Salmon appears to have been a filter feeder, much like modern-day baleen whales. It had specialized structures in its gills to strain tiny organisms from the water. This combination of filter-feeding and giant size mirrors the evolution of the largest animals on Earth today – blue whales.

One surprising discovery is that both male and female O. rastrosus possessed these impressive spike-like teeth.

“We also stress that females and males alike possessed the enormous, tusk-like teeth. Therefore, the sexes were equally fearsome,” notes Brian Sidlauskas, professor and curator of fishes at Oregon State University.

This is unlike many modern species, where males often have more pronounced weapons or ornaments.

This reimagining of O. rastrosus provides a vivid new glimpse into prehistoric ecosystems. Imagine ancient Pacific Northwest rivers teeming with these massive, spike-adorned salmon during their spawning runs. Their presence would have had profound effects on the entire food web, from the prey they consumed to the predators and scavengers that fed upon them.

“I’m delighted that we have been able to put a new face on the giant spike-tooth salmon, bringing knowledge from the field in Oregon to the world,” adds Edward Davis, associate professor of earth sciences at the University of Oregon and director of Condon Collection at the UO’s Museum of Natural and Cultural History.

The Spike-Toothed Salmon serves as a reminder that the natural world is often stranger and more wonderful than we can imagine. It also highlights the importance of new discoveries and technologies in paleontology. A single well-preserved fossil can completely change our understanding of extinct creatures and ancient ecosystems.

As we face modern challenges like climate change and habitat loss, understanding the diversity and adaptations of ancient life becomes increasingly valuable. The story of O. rastrosus shows us just how dramatically species can evolve to fill ecological niches. It reminds us that the Earth has seen radical changes before and that life finds a way to adapt – sometimes in truly spectacular fashion.