People love prehistoric animals, especially dinosaurs. But they are also only too happy to give their hearts to other creatures from evolutionary history, especially if they are big and bizarre enough. We like mammoths, for example, because they were so shaggy and plodded together across the tundra. Among prehistoric fish, there are only a few that excite laypeople, such as the basking shark Megalodon, which made it into the cinema as the super great white shark.
Another spectacular prehistoric fish was the so-called saber-toothed salmon. The approximately 2.5 meter long ancestor of today’s trout and salmon had, in addition to its normal teeth, two distinctive teeth that protruded downwards like the fangs of a saber-toothed tiger and gave it its colloquial name. You thought so!
But the scientists apparently made a mistake in the orientation of the brilliant extra teeth. Newer, more complete finds of skulls of giant salmon, which lived around five to twelve million years ago, and their analysis using computer tomography now show that the supposed sabers did not stand vertically downwards, as expected, but rather jutted out to the side like large thorns protruding from the jaw. The paleontologists speculate about what function they might have fulfilled in a current article in the renowned science magazine PLOS One.
They could possibly have served as a defense for the big fish. Like salmon living today, the ancient salmon spent a large part of their lives in the sea and migrated upstream to spawn during the mating season. Due to their high fat content, they were probably popular prey, for example for large sharks. But the ancient salmon were apparently by no means defenseless: With their very muscular bodies, they could move their heads powerfully from right to left and thus use their thorn-shaped tusks like a cutting weapon.
The researchers also suspect that the prehistoric fish also used their side teeth to fight for mating partners. In modern salmon, it is only the males who develop certain body attributes during mating season, such as a distinctive, hook-shaped lower jaw (so-called hooked salmon) for biting or a high dorsal crest to ward off attacks. In the prehistoric sea and river, however, there was still anatomical equality; both sexes had tusks growing on their heads.
The fish may also have used their extra teeth like a kind of plow to stir up nutritious sediment. In contrast to modern salmon and trout, which prey on insects, their ancestors probably primarily consumed plankton or the partially decomposed remains of other organisms that rained down to the bottom of the waters in which they lived. Whale sharks, manta rays and baleen whales impressively demonstrate that fish and aquatic mammals that eat small amounts of food can reach an impressive size.
Due to the new results, the scientists were forced to abandon the image of the swimming saber-toothed fish. Nevertheless, the great ancient salmon remains an impressive relic of evolutionary history. And two stately side tusks are quite spectacular.
