Fossil of rare armor-plated worm found

The complete skeleton of the worm (plumulitid machaeridian,) a member of the group that includes earthworms, bristleworms and leeches, was unearthed in downtown Ottawa by an amateur fossil collector prospecting for fossils in rock from a temporary building excavation.

"Such significant new fossils are generally discovered in remote or little studied areas of the globe, requiring difficult journeys and a bit of adventure to reach them" said Jakob Vinther of Yale University, lead author of a paper describing the specimen. "Not this one though. It was found in a place that has an address rather than map co-ordinates!"

Vinther said Plumulitid machaeridians look like modern bristleworms, with stout walking limbs bearing long bundles of bristles, but on their back they carried a set of mineralized plates.

"The plates themselves were rigid, but they could move relative to one other, providing plumulitids with a protective body armor very similar to the flexible metal armor invented by humans 450 million years later," Vinther said.

"Machaeridian body armor is unique among annelids, and probably helped them to succeed as ubiquitous components of marine ecosystems for more than 200 million years."

The discovery is reported by Vinther and Dave Rudkin of Toronto's Royal Ontario Museum in the journal Paleontology.

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