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Rare fossil offers clues to past
September 18, 2003 - A new, rare fossil of a prehistoric sea creature with
eyes like "twin towers" sheds light on how it lived more than 395 million
years ago, says a University of Alberta researcher.
Dr. Brian Chatterton, one of the world's leading experts on trilobites and
a professor in the U of A Faculty of Science, reports on the discovery of
the only known complete specimen of a particular trilobite in this week's
edition of Science.
Chatterton was recently contacted by Richard Fortey of the Natural History
Museum in London after a commercial dealer offered the specimen--phacopoid
trilobite Erbenochile--for sale. Fortey turned to Chatterton to learn
exactly what and how rare the specimen was. They soon discovered that its
several exaggerated and unique features made it of "more than normal
interest" to paleontologists.
Unlike other trilobites, this specimen has eyes that stand up like twin
towers or have extensions of their palpebral lobes that stretch outward
above the eye.
"These lobes would have acted like a lens shade on a camera or a baseball
hat brim on humans. They prevented unwanted light from entering the lenses
that would otherwise bounce around and cause a fuzziness in the image seen
by the trilobite animal," said Chatterton. "These trilobites lived at a
time--395 million years ago--when large predatory fishes capable of
crushing shelled animals were becoming common for the first time, and
perhaps acute vision allowed these trilobites to escape or hide from being
Despite some suggestion that the species was nocturnal, this finding
provides evidence that the trilobite may have been most active during
daylight hours. Distinct and unusual features such as these seldom appear
in evolution as random occurrences without offering some practical use,