508 million-year-old fossil a gripping find

What do ants, centipedes and lobsters have in common? They’re all masters of the pincer movement, members of the most abundant and diverse group of organisms on Earth. Known as mandibulates, their common trait is a pair of specialised appendages (mandibles) for grasping, crushing and cutting food. Which is why the discovery of this exceptionally well-preserved fossil, named Tokummia katalepsis, by Canadian palaeotolongists is so important.

“Before now we’ve had only sparse hints at what the first arthropods with mandibles could have looked like,” explains Cédric Aria, of the University of Toronto, “and no idea of what could have been the other key characteristics that triggered the unrivaled diversification of that group.”

The fossil, from 508 million-year-old sedimentary rocks near Marble Canyon, British Columbia, shows the 10-centimetre-long sea creature with broad serrated mandibles as well as large but specialised anterior claws called maxillipeds. “The pincers of Tokummia are large, yet also delicate and complex,” Aria says, “reminding us of the shape of a can opener, with their couple of terminal teeth on one claw, and the other claw being curved towards them.”

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