Blacksburg, Va. -- The fossil record seems to indicate that the diversity of marine creatures increased and decreased over hundreds of millions of years in step with predator-prey encounters, Virginia Tech geoscientists report in the Proceedings of the National Academy of Science.
For decades, there has been a debate between paleontologists, biologists, and ecologists on the role of ecological interactions, such as predation, in the long term patterns of animal evolution.
John Warren Huntley, a postdoctoral scientist in the Department of Geosciences at Virginia Tech, and Geosciences Professor Micha Kowalewski decided to look at the importance of ecology by surveying the literature for incidents of predation in marine invertebrates, such as clams and their relatives.
Today, certain predators leave easy to identify marks on the shells of their prey, such as clean, round holes, said Huntley. Such holes drilled by predators can also be found in fossil shells.
The researchers also looked for repair scars on the shells of creatures that survived an attack.
The study was conducted by looking at studies which reported the frequency of drill holes and repair scars in fossil species from the last 550 million years.
First Huntley and Kowalewski found that predation increased notably about 480 million years ago, some 50 million years earlier than previous studies have found. The earlier studies were based on changes in morphology predators with stronger claws and jaws and prey with more ornamented shells. We looked at the frequency of attacks, which increased about 50 million years before the changes in armor, said Huntley.
But the most notable discovery is the observation that the incidence of drill holes and repair scars are strikingly parallel to Sepkoskis diversity curve for marine invertebrates. This diversity curve, compiled by the late Jack Sepkoski of the University of Chicago, records the or
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