Oregon, United States

As per a new study, a massive prehistoric salmon that went extinct millions of years ago had tusk-like teeth that protruded from either side of its face.

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The study published in the journal PLOS One shows that the fish had teeth that projected sideways and resembled the tusks of a warthog.

Oncorhynchus rastrosus aka massive 'sabre-toothed salmon'

The fish called 'Oncorhynchus rastrosus' as per scientists, was the largest ever to live on Earth. By some estimates, it could reach enormous lengths of up to 8.8 feet (2.68 metres). 

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This is more than double the size of the Chinook salmon (Oncorhynchus tshawytscha), the largest salmon alive today — it typically grows around three feet (0.9 meters) long.

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It stalked the seas and streams of the Micone epoch — a time interval of global warmth, relative to today — about five million years ago.

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Exceptional chompers

Oncorhynchus rastrosus had exceptional teeth, which have long intrigued scientists. 

The fish was first discovered in 1972. Based on the anatomy of fossilised skulls, researchers back then believed that the salmon's teeth curved downward, similar to that of sabre-toothed cats. This led to the fish commonly being called the "sabre-toothed salmon".

However, CT scans of some newer fossils confirmed that the around two-inch long curved teeth were more like spikes or a warthog's tusks.

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While the scientists are not sure what these tusks were used for, they believe that these were used to fight off other salmons or predators. Other theories suggest that females of the species might have used them to dig nests for their eggs, or possibly to help both sexes swim upstream to reproduce.

In a conversation with PopSci, study co-author and University of Oregon palaeobiologist Edward Davis speculated that when swimming upstream, "they could maybe hook the spikes on something and take a rest without having to use any energy."

"It's sort of like if you're holding on to the side of the swimming pool."

As the Earth cooled in the late Miocene, Oncorhynchus rastrosus went extinct. Climate change probably led to a decrease in resources, making it difficult for them to maintain their large bodies. 

(With inputs from agencies)