At 400 pounds and 8 feet long, this salmon would be good eating—if only it wasn’t extinct. Oncorhynchus rastrosus, the giant spike-toothed salmon, lived in California for around 7 million years, going extinct 5 million years ago. This monster salmon, which is closely related to modern Pacific salmon and actually a member of the same genus, luckily left behind clues about its life and behaviors in its fossil remains. New research by paleontologist Julia Sankey at California State University Stanislaus and colleagues in PaleoBiosgets to the bottom of how this behemoth lived and bred.

Spike-teeth or saber-teeth? When this salmon species was first described, researchers called it a “sabertooth salmon” because of the long, robust teeth on its upper jaw, but actually they point outward instead of downward. This makes them more spike-teeth rather than sabers. The teeth were around 1.5 inches long and pointed straight out from the top of the jaw– likely used for breeding, digging and fighting. Living Pacific salmon fight with each other during mating season for the breeding rights to females, but did O. rastrosus do the same?

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