Web address:
http://www.sciencedaily.com/releases/2010/11/
101109172349.htm
Oldest Fossilized Shrimp: Geologists Study Rare Well-Preserved Creature Showing
Muscles
enlarge
The fossil shrimp from Oklahoma and a recent shrimp. (Credit: Rodney
Feldmann/NOAA)
ScienceDaily (Nov. 9, 2010) Rodney Feldmann, professor emeritus, and Carrie
Schweitzer, associate professor, from Kent State University's Department of
Geology report on the oldest fossil shrimp known to date in the world. The
creature in stone is as much as 360 million years old and was found in
Oklahoma. Even the muscles of the fossil are preserved.
Their study will be published in Journal of Crustacean Biology.
"The oldest known shrimp prior to this discovery came from Madagascar,"
Feldmann said. "This one is way younger, having an age of 'only' 245 million
years, making the shrimp from Oklahoma 125 million years older."
The fossil shrimp, having a length of about 3 inches, was found by fellow
paleontologist Royal Mapes of Ohio University and his students. Feldmann and
Schweitzer named the fossil after him: Aciculopoda mapesi.
The discovery is also one of the two oldest decapods ('ten footed') to which
shrimp, crabs and lobsters belong. The other decapod, Palaeopalaemon newberryi,
is of similar age and was found in Ohio and Iowa. "The shrimp from Oklahoma
might, thus, be the oldest decapod on earth," Feldmann explained.
The fossil is a very important step in unraveling the evolution of decapods.
However, more finds are necessary. "The common ancestor of the two species can
probably be found in rocks that once formed the old continent Laurentia,"
Schweitzer said. "Nowadays, these rocks can be found primarily in North America
and Greenland. Who's going to find it? Possibly by one of the numerous amateur
collectors, who often graciously donate specimens to science."
The description of the fossil is not only remarkable because of its age, but
also due to its preservation. In this case, the muscles that once made up the
tail part of the shrimp were preserved. This is extremely rare in fossils.
Feldmann knows why the muscles are still visible. "When the animal died, it
came to rest on the seafloor," he said. "The muscles then were preserved by a
combination of acidic waters and a low oxygen content as the animal was buried
rapidly."
The shrimp lived in deeper waters of the ocean where currents were too weak to
destroy the shrimp. Other animals that were found in the same rock include the
extinct ammonites, nautiloids, brachiopods and sponges.
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The above story is reprinted (with editorial adaptations by ScienceDaily
staff) from materials provided by Kent State University.
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Kent State University (2010, November 9). Oldest fossilized shrimp: Geologists
study rare well-preserved creature showing muscles. ScienceDaily. Retrieved
November 10, 2010, from http://www.sciencedaily.com
/releases/2010/11/101109172349.htm
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