In modern ecology, the removal or addition of a predator to an ecosystem can produce dramatic changes in the population of prey species. For the first time, scientists have observed the same dynamics in the fossil record, thanks to a mass extinction that decimated ocean life 360 million years ago.
What was bad for fish was good for the fish's food, according to a paper published today in Proceedings of the National Academy of Sciences. Researchers from the University of Chicago, West Virginia University, and The Ohio State University find 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.
"This is the first time that specific, long-term predator-prey interactions have been seen in the fossil record," said Lauren Sallan, graduate student in the Department of Organismal Biology and Anatomy at the University of Chicago and lead author. "It tells us a lot about the recovery from mass extinctions, especially mass extinctions that involved a loss of predators."
Paleontologists know the Devonian Period, which spanned from 416 to 359 million years ago, as the Age of Fishes, a time of astonishing diversity for marine vertebrate species. That thriving world was devastated by the Hangenberg event, a mass extinction of unknown origin that set the stage for modern biodiversity.
But some species survived the carnage of the Hangenberg event. The next 15 million years in the fossil record are dominated by crinoids, species similar to modern sea lilies and related to starfish. So abundant and diverse were these marine animals that the period is known as the Age of the Crinoids; entire limestone deposits from the era are made up of crinoid fossils.
"We've been puzzled for many years as to why there were so many species and specimens of crinoids," said study co-author Thomas Kammer, PhD, Eb
|Contact: Robert Mitchum|
University of Chicago Medical Center