New lobster-like predator found in 508 million-year-old fossil-rich site | EurekAlert! Science News

From EurekAlert! | University of Toronto | March 27, 2015

TORONTO, ON – What do butterflies, spiders and lobsters have in common? They are all surviving relatives of a newly identified species called Yawunik kootenayi, a marine creature with two pairs of eyes and prominent grasping appendages that lived as much as 508 million years ago – more than 250 million years before the first dinosaur.

The fossil was identified by an international team led by palaeontologists at the University of Toronto (U of T) and the Royal Ontario Museum (ROM) in Toronto, as well as Pomona College in California. It is the first new species to be described from the Marble Canyon site, part of the renowned Canadian Burgess Shale fossil deposit.

Yawunik had evolved long frontal appendages that resemble the antennae of modern beetles or shrimps, though these appendages were composed of three long claws, two of which bore opposing rows of teeth that helped the animal catch its prey.

“This creature is expanding our perspective on the anatomy and predatory habits of the first arthropods, the group to which spiders and lobsters belong,” said Cedric Aria, a PhD candidate in U of T’s Department of Ecology & Evolutionary Biology and lead author of the resulting study published this week in Palaeontology. “It has the signature features of an arthropod with its external skeleton, segmented body and jointed appendages, but lacks certain advanced traits present in groups that survived until the present day. We say that it belongs to the ‘stem’ of arthropods.”

The study presents evidence that Yawunik was capable of moving its frontal appendages backward and forward, spreading them out during an attack and then retracting them under its body when swimming. Coupled with the long, sensing whip-like flagella extending from the tip of the claws, this makes the frontal appendages of the animal some of the most versatile and complex in all known arthropods.

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