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Fossils Show How Boneworms Dined on Ancient Sea Serpents

Bone-eating worms that can devour an entire whale carcass were also feasting on prehistoric reptiles more than 100 million years ago, a new study finds.

No one knows when the first Osedaxworms started scavenging sunken carcasses on the ocean floor. The bizarre, finger-length worms are soft-bodied and leave no fossils behind, so their origin is lost to time. But traces of the creatures' strange dining habits can be detected on ancient fossils.

Today, Osedax worms feast on dead whales. But 100 million years ago, they bored into the bones of sea turtles and the marine reptiles known as plesiosaurs, scientists from Plymouth University report Wednesday in the journal Biology Letters. [The 12 Weirdest Animal Discoveries]

Lead study author Silvia Danise hunted through gnarly bones in the drawers and displays of the Sedgwick Museum in Cambridge to find fossils gnawed by Osedax. "I was looking for things that were weathered, or with an irregular surface, which is what happens in the modern bones that are attacked by Osedax," said Danise, a paleontologist who is now at the University of Georgia in Athens.

For creatures with no mouths or guts, bone-eating worms are amazingly effective eaters. (Some species use acid instead.) The worms were discovered on the seafloor off the coast of California, gorging on a whale.

How the worms eat remains a mystery, but scientists think the creatures extend fleshy tendrils laced with symbiotic bacteria into the bone. The tendrils carve through the nutrient-rich tissue and extract collagen and fat with help from the bacteria. This eating action leaves behind an empty pocket that resembles a tree stump with roots.

Danise hit pay dirt with several old bones from the end of the Mesozoic era, before the Cretaceous mass extinction that killed off the dinosaurs and the plesiosaurs 65 million years ago. There were distinctive round boreholes and rootlike cavities in bones from turtles and plesiosaurs.

— Becky Oskin, LiveScience

This is a condensed version of a report from LiveScience. Read the full report. Follow Becky Oskin on Twitter. Follow Live Science on @Twitter, Facebook and Google+.