World Decapod Experts Document Shrimp Fossil Older Than Dinosaurs
The oldest shrimp fossil discovered to date has been documented by Dr. Carrie Schweitzer, associate professor in the Department of Geology at Kent State University at Stark, along with her husband, Kent State Emeritus Professor Dr. Rodney Feldmann.
The fossil, drawn from the dark-colored, siliceous Woodford Shale in southern Oklahoma, was discovered by Ohio University paleontologist Dr. Royal Mapes, and sent to Schweitzer and Feldmann for identification.
Through a grant from the National Science Foundation (NSF), Schweitzer and Feldmann went to work cleaning, photographing and drawing sketches of the fossil, while also examining its tail segments, legs, muscle structure and rostrum (a spine-like protrusion from the head). Remarkably preserved, the specimen displays rare soft tissue detail. The fossil was dated to the Devonian Period, making the fossil the earliest known shrimp and one of the two oldest decapods, both from North America.
"This recent discovery means decapods date back as far as 360 million years â€“ much earlier than dinosaurs, and much earlier than traditional views held," Schweitzer said.
Over the course of three months, Schweitzer and Feldmann developed a report on their findings, "The Oldest Shrimp and Remarkable Preservation of Soft Tissue," which was published in the November 2010 Journal of Crustacean Biology.
Other researchers, working under the same NSF grant are developing a DNA-based family tree of all decapods. The fossil Schweitzer and Feldmann identified, named Aciculopoda mapesi, after its discoverer, permit these researchers to put a geologic age on shrimp and provide a molecular clock, or a starting point, for further research.
"Now we know there are more than 150 million years of shrimp fossil records that are missing," Schweitzer said. "We need to look more closely at arthropod evolution, which I believe will result in new and surprising results about evolutionary patterns in general. We have a lot more fossils to find.
Schweitzer and Feldmann presented the findings of their research at the Geological Society of America's 2010 Annual Meeting and Exposition, Reaching New Peaks in Geoscience. The fossil shrimp now resides in the Smithsonian Institution, where Schweitzer and Feldmann worked as visiting researchers in 2008.
The husband-wife team believes that more fossils of this kind will be found in black shale and Triassic rocks, in which soft-bodied animals can be preserved. With upcoming plans to dig in Argentina, the researchers hope to find more specimens that will help fill the incomplete decapod fossil records.
Schweitzer, who conducted her thesis and dissertation on Pacific Coast decapods, has published nearly 100 papers on the decapoda. Together with Feldmann, whose research began in the 1970s, they have accumulated an encyclopedic knowledge of decapod records, earning them the nickname, "The Decapod People," by their peers internationally. During the past five years, Schweitzer and Feldmann have visited nearly every major decapod collection in the world.
During her sabbatical in spring 2010, Schweitzer began writing a diagnosis for every genus, family and superfamily of decapods, and she is also working on the decapoda volume in the encyclopedia of all invertebrate animals, "The Treatise on Invertebrate Paleontology," as the most recent documentation is outdated.
The goal of Schweitzer and Feldmann's research is to learn more about what has made it possible for this group of animals to survive so long.
Why is it that we have shrimp alive today, but not dinosaurs? What can shrimp and their relatives tell us about resilience, adaptations and survivability?
"If we could understand why these animals are so resilient, could that teach us something about surviving diseases or environmental catastrophes?" Schweitzer said.