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Prehistoric lobster found in Burgess Shale fossil bed

The creature's discovery offers a glimpse of the period of geologic time when life on Earth began to proliferate and diversify at quickening pace.

By Brooks Hays

TORONTO, March 28 (UPI) -- Researchers in Canada have unearthed an ancient marine creature they say is the common ancestor of a diverse range of modern species, including butterflies, spiders and lobsters.

The prehistoric species, Yawunik kootenayi, was discovered in the Burgess Shale Formation, located in the Canadian Rockies of British Columbia -- one of the most fertile fossil sites in the world. The newly unearthed fossil dates back 509 millions years ago, some 250 million years before the first dinosaur appears in the fossil record.

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Yawunik was discovered at the Marble Canyon site -- part of the larger shale formation -- inside British Columbia's Kootenay National Park.

Outfitted with long frontal appendages like the antennae protruding from the heads of shrimp, Yawunik appears something like a cross between a lobster and a centipede. But unlike a shrimp or beetle's antennae, Yawunik's appendages weren't solely feelers, they were also hunting tools.

Whereas many of Yawunik's relatives (lobsters, for example) would go on to evolve specialized appendages for various tasks -- some of pinching prey, some for maneuvering, some for sensing -- Yawunik opted for the all-inclusive approach.

Yawunik's frontal appendages formed three claws, two of them accessorized with rows of teeth, allowing the strange crustacean-like creature to catch and dice up its prey. The ancient animal likely tucked them under its body when it swam and spread them out when capturing prey.

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"Unlike insects or crustaceans, Yawunik did not possess additional appendages in the head that were specifically modified to process food," explained lead study author Cedric Aria, a researcher and PhD candidate in the University of Toronto's department of ecology and evolutionary biology. "Evolution resulted here in a combination of adaptations onto the frontal-most appendage of this creature, maybe because such modifications were easier to acquire."

"We know that the larvae of certain crustaceans can use their antennae to both swim and gather food," Aria added. "But a large active predator such as a mantis shrimp has its sensory and grasping functions split up between appendages."

Yawunik's discovery offers a glimpse of the period of geologic time when life on Earth began to proliferate and diversify at quickening pace.

"Yawunik and its relatives tell us about the condition existing before such a division of tasks among parts of the organism took place," Aria said.

The research was published in the latest issue of the journal Palaeontology.

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