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Newly discovered 400-million-year-old giant worm had killer jaws

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Meet Websteroprion armstrongi

An artist’s rendering of W. armstrongi attacking a fish about 400 million years ago
James Ormiston

Scientists have discovered a new species of extinct, marine worms that had snapping jaws and grew to an estimated 3 feet in length. The species, called Websteroprion armstrongi, lived some 400 million years ago — and is believed to be Earth’s oldest “Bobbit worm.” The species is described in a study published this week in the journal Scientific Reports.

Bobbit worms are giant marine monsters that dwell on ocean floors to this day. They can be as long as 10 feet, and their hunting strategy consists of hiding beneath the sand and then shooting out a fraction of their body to attack fish and octopi. Their name apparently comes from Lorena Bobbitt, a US woman who cut off her husband’s penis with a knife in 1993. The nickname was chosen because the worm’s jaws “resemble scissors, or because the exposed portion [of the body] resembles an erect penis,” according to a 2011 paper.

The newly-discovered species, W. armstrongi, was identified thanks to several ancient jaw fossils stored at the Royal Ontario Museum in Toronto. The fossilized jaws reached about 0.4 inches in length — the largest jaws recorded in ancient marine worms. The jaws’ features also "unambiguously" showed that they belonged to a new species, according to the study. From the jaw size, the researchers estimated that the body of W. armstrongi was over 3 feet.

"Gigantism in animals is an alluring and ecologically important trait, usually associated with advantages and competitive dominance,” lead author Mats Eriksson from Lund University said in a statement. "It is, however, a poorly understood phenomenon among marine worms and has never before been demonstrated in a fossil species.”

The fossil jaws
Luke Parry

The jaw fossils were excavated near the town of Moosonee, Canada, in 1994, by Ontario Geological Survey researcher Derek Armstrong. The new giant worm species is named after him, as well as Alex Webster, a bassist in the death-metal band Cannibal Corpse, whom the study authors call “a ‘giant’ of a bass player.”

"This is fitting also since, beside our appetite for evolution and paleontology, all three authors have a profound interest in music and are keen hobby musicians," co-author Luke Parry, from the University of Bristol's School of Earth Sciences, said in a statement.