It is estimated that O. rastrosus was the largest salmon ever to have existed, reaching a length of up to 2.7 m and a weight of 200 kg), and lived between 11 and 5 million years ago. years in the waters of the Pacific Northwest of North America and Japan.
This species was first described in 1972 based on fossils found in Oregon. At that time, scientists noticed two large sharp teeth protruding from the end of her snout.
Mainly because these teeth were found separated from the rest of the fossilized remains, it was thought that they were directed inward into the mouth, like bites. Due to this characteristic, the fish earned the common name – “saber-tooth salmon”.
But according to a recent study led by Philadelphia College of Osteopathic Medicine researcher Dr. Kerin Claeson, it has now been determined that the teeth protruded straight out to either side like fangs. This conclusion was made based on computer tomography of the original fossils and later discoveries O. rastrosus analysis of fossils in which the teeth were still intact from the skull.
It is thought that salmon first used their fangs for defense against predators and/or to defend a territory against members of their own species. Scientists also assume that the fish used their fangs to dig nests in river bottoms and swim up rivers to spawn. This conclusion was made based on the fact that fossils found in marine environments have smaller tusks than those found in freshwater.
Whatever else the fangs were used for, it almost certainly wasn’t for killing prey. Without expressive teeth, O. rastrosus had bony structures called gill spines that modern salmon use to filter their main food, plankton, from the water passing through their gills.
In light of their new findings, the researchers now suggest: Oncorhynchus rastrosus change the common name to “spiny-toothed salmon” (eng. spike-toothed salmon)
“We’ve known for decades that these extinct salmon from Central Oregon were the largest salmon that ever lived,” Claeson says. “Finds like ours show that they probably weren’t very gentle giants.”
The article was recently published in the journal PLOS ONE.
Adapted from New Atlas.
