Kent State professor dates 360 million year old shrimp

Maura Zurick

Kent State geology professor Rodney Feldmann helped date a 360 million-year-old fossilized shrimp that was discovered in Oklahoma in the mid 1990s.

The shrimp was uncovered by Ohio University professor Royal H. Mapes during a field trip with students looking for cephalopods, a form of mollusc. Mapes said he found the shrimp while looking for other fossilized sea critters in Oklahoma because at one time, the state was under sea level, as was most of North America, due to a major flood in the late Cretaceous period.

Mapes said because of the geographic location and type of organism, he knew that it was unusual but did not realize how important at the time.

“The specimen was in a shale quarry lying on the surface just waiting for someone to collect it,” Mapes said. “I was looking for other fossils at the time. I did not know of the special information that this specimen would reveal, but I did note that it was ‘shrimp-like’ and probably important. After I returned to Ohio University after the expedition, the specimen was sent to a fossil arthropod specialist, and after many years, that specialist forwarded it to Feldmann.”

Feldmann examined the shrimp and dated it back to over 360 million years, 125 million years older than any other fossilized morsel, making it the oldest decapod ever found. Feldmann said the fossil is in good condition, even showing the shrimp’s tail muscles and hard shell. The shrimp is about three inches long and preserved in stone. Before Feldmann’s dating of the fossil, the shrimp was estimated to be about 245 million years old.

“It was very rapidly buried in an environment where no scavengers could get at it, where the oxygen level was very low, and where the pH was also low,” Feldmann said. “These conditions permitted almost instantaneous entombment and preservation within days or weeks.”

Feldmann said the discovery is important because it adds millions of years to the evolution of shrimp and maybe other sea life, as the shrimp was living during the time of squids and other cephalopods.

The fossil will remain at Kent State in the geology department for the time being. Feldmann does not know where the shrimp will eventually be placed.

Contact Maura Zurick at [email protected].