September 11, 2019 2:16 pm
Updated: September 11, 2019 11:57 pm

‘Staring at me:’ Oldest known spider ancestor found in Burgess Shale

Mollisonia plenovenatrix preserved in dorsal view, showing the large eyes, the walking legs and the small chelicerae at the front. British Columbia's famed Burgess Shales have yielded another ground-breaking fossil find — this time the oldest known ancestor of today's spiders and scorpions.

THE CANADIAN PRESS/HO-© Royal Ontario Museum- Jean-Bernard Caron
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Correction: This article previously reported that the Burgess Shale is located in Alberta. It’s located in Yoho National Park in British Columbia. 

British Columbia’s famed Burgess Shale has yielded another ground-breaking fossil find — this time the oldest known ancestor of today’s spiders and scorpions.

Two scientists from the Royal Ontario Museum pried loose the well-preserved 500-million-year-old fossil from the area’s abundant deposits.

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They describe the thumb-sized beastie as a fierce predator, equipped with tiny pincers in front of its mouth to grab, kill and eat its prey.

The underside of this modern-day horseshoe crab, Limulus polyphemus, also known as the Atlantic horseshoe crab, shows its pincer type chelicerae at the top of the photos. In the lower half of the photo, a section of book gills can be seen by lifting its ridged protective flaps called opercula. Opercula are absent in Mollisonia and therefore represent a further step in the evolution of chelicerates. British Columbia’s famed Burgess Shale has yielded another ground-breaking fossil find — this time the oldest known ancestor of today’s spiders and scorpions.

THE CANADIAN PRESS/HO-© Royal Ontario Museum- Brian Boyle

It’s those pincers that put it at the root of a family tree that now boasts more than 115,000 different species.

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The preservation and detail in the fossil allowed the researchers to definitively link it to modern animals.

Paleontologist Jean-Bernard Caron says they found the specimen when the reflective minerals that replaced its eyes blinked at them from the rock.

© 2019 The Canadian Press

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