Researchers considered whether a change in the environment, such as water temperature or depth, could explain the crinoid explosion, Kammer said. Changes in predation were also proposed, but hard to test using the fossil record.
"You don't actually find the evidence of a fossil fish with a crinoid in its mouth very often," Kammer said.
The riddle was solved through multi-institutional collaboration and data-sharing. A database of crinoid diversity in the fossil record assembled by Kammer and William Ausich, PhD, study co-author and Professor of Earth Sciences at Ohio State University, was compared to a vertebrate dataset created by Sallan.
When the datasets were placed side by side and analyzed, a clear relationship emerged. As fish populations thrived in the Devonian, crinoid diversity and abundance remained low despite favorable conditions. But after the Hangenberg event devastated fish species, crinoids thrived, diversifying and multiplying. The data suggests the ripple effects of a mass extinction upon ecosystems can last millions of years.
"This study demonstrates a clear example of processes that operate in ecological time predator-prey relationships becoming significant in evolutionary time," Ausich said. "This means that ecological patterns and processes taking place today may have very long-reaching evolutionary effects. And although that idea may not seem particularly surprising at first, respected evolutionary biologists have long argued that it was not possible."
Eventually, the success of crinoids came to an end. As fish species recovered to previous levels, crinoid populations declined in tandem further evidence for typical predator-prey dynamics known as Lotka-Volterra cycles in modern ecology.
Fossils even suggest that the long period
|Contact: Robert Mitchum|
University of Chicago Medical Center