New information about a mass extinction that decimated ocean life 360 million years ago is giving researchers further insight into long-term predator-prey relationships.
What was bad for fish was good for the fish’s food, according to a paper published in the May 17 edition of “Proceedings of the National Academy of Sciences.” Researchers from West Virginia University, the University of Chicago and Ohio State University found that the mass extinction, known as the Hangenberg event, produced a “natural experiment” in the fossil record with results that mirror modern observations about predator-prey relationships.
“The effects of predation not only cause individual species to either adapt or go extinct, predation can also cause entire groups of organisms to either adapt or go extinct,” said study co-author Thomas Kammer, Eberly College Centennial Professor of Geology at WVU. “Also, when mass extinction greatly affects either predator or prey groups, we see a corresponding impact in the other group.”
The partnership began when Kammer’s father sent him a news article about a paper co-authored by Lauren Sallan, a graduate student in the Department of Organismal Biology and Anatomy at the University of Chicago. The paper explained some anomalies Kammer had observed in his own research, and he contacted her to collaborate.
William Ausich, professor of earth sciences at Ohio State University, and Concord University lecturer and researcher Lewis Cook also worked on the study. Cook, a 1973 WVU graduate, participated in the investigation when he returned to the university to pursue his doctoral degree in paleontology.
“This is the first time that specific, long-term predator-prey interactions have been seen in the fossil record,” said Sallan, the paper’s lead author. “It tells us a lot about the recovery from mass extinctions, especially those that involved a loss of predators.”
The Devonian Period was a time of astonishing diversity for marine vertebrate species. That thriving world was devastated by the Hangenberg event, a mass extinction of unknown origin 360 million years ago that set the stage for modern biodiversity. The next 15 million years in the fossil record are dominated by crinoids, a surviving species similar to modern sea lilies and related to starfish.
“We’ve been puzzled for many years as to why there were so many species and specimens of crinoids,” said Kammer. “There had to be some underlying evolutionary and ecological reason for that.”
Datasets revealed that as fish populations thrived in the Devonian Period, crinoid diversity and abundance remained low. However, after the Hangenberg event devastated fish species, crinoids thrived, diversified and multiplied.
As fish species recovered to previous levels, crinoid populations declined. Fossils suggest that the long period of dominance had left the crinoids vulnerable to a new predator strategy. The hard armored shells they had developed to defend against fish with sharp “shearing” teeth was useless against new species of fish that used “crushing” teeth.
“Through scientific research, we become more knowledgeable about our world and how to deal with its adversaries,” Cook said. “It is also intensely rewarding to discover new and original information that may contribute to the overall success of life on Earth.”
The paper, “Persistent Predator-Prey Dynamics Revealed by Mass Extinction,” appeared in the journal for the week of May 17, 2011.
Funding for the research was provided by the National Science Foundation, the Paleontological Association, the Paleontological Society, the American Society of Ichthyologists and Herpetologists, and the Evolving Earth Foundation.
For more information, contact Thomas Kammer, geology professor at WVU, at (304) 293-9663 or Thomas.Kammer@mail.wvu.edu.
This release was written in collaboration with Robert Mitchum, senior science reporter at the University of Chicago.
-WVU-
6/3/11
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Robert Mitchum, senior science writer at the University of Chicago, robert.mitchum@uchospitals.edu.
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