Largest known trilobite - a new species of Isotelus - image copyright Manitoba Museum
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The Discovery and Excavation

Bob Elias Home Page

Department of Geological Sciences

  The World's Biggest Trilobite

A team of Canadian paleontologists working along Hudson Bay in northern Manitoba has discovered the world's largest recorded complete fossil of a trilobite, a many-legged, sea-dwelling animal that lived 445 million years ago. The giant creature is more than 70 cm long (about 28 inches), 70 percent larger than the previous record holder. "This is an important and amazing find," says Bob Elias, a professor in the department of geological sciences at the University of Manitoba. "It looks like a huge bug!"

Reconstruction of a trilobite living on the sea bottom. It may have eaten shrimp and worms.

Trilobites are an extinct group of arthropods with hard, jointed external skeletons, distantly related to crabs, scorpions, and insects. They are among the most familiar fossils of the Paleozoic Era, about 545-250 million years ago. "The majority of trilobites were between three and ten centimetres long," notes Dave Rudkin, assistant curator of paleobiology at the Royal Ontario Museum in Toronto. "Their fossil remains are eagerly sought by amateur and professional paleontologists alike."

Scale drawings of giant trilobites from northern Manitoba (a,c), other big species reported from elsewhere (b,d,e), and a typical large trilobite (f). A house cat is shown for size comparison.

The record-setting trilobite was found and recovered during a long-term field project investigating fossils along an ancient marine coast of Late Ordovician age exposed near Churchill, Manitoba. "Four hundred and forty-five million years ago, this now frozen and windswept area was a thriving tropical haven for life along what was then the Earth's equator," says Graham Young, associate curator of geology at the Manitoba Museum of Man and Nature and an adjunct professor at the University of Manitoba.

Field Crew Shot

1998 field crew: (L-R) David Wright, Graham Young, Bob Elias, Dave Rudkin, Curtis Moffat, Janis Klapecki, Ed Dobranski.

The giant trilobite represents a new species of the genus Isotelus. Elias notes: "This remarkable discovery adds to our knowledge of biodiversity following the Ordovician evolutionary radiation, one of the greatest diversifications in the history of life. The huge species existed just before the end of the Ordovician Period, when Isotelus and many but not all other trilobites disappeared in a great mass extinction. Studies of these events help us understand more about global environmental changes and their effects on the biosphere."

This research project is led by Graham Young and Bob Elias; the trilobites are being studied by Dave Rudkin. We acknowledge financial support from the Natural Sciences and Engineering Research Council of Canada, the University of Manitoba, the Manitoba Museum Foundation, and the Royal Ontario Museum Foundation.

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