Shells can survive a remarkably long time in the fossil record, such that if a person slurped up several oysters and carefully saved the shells, scientists millions of years into the future might be able to document the ancient meal.
(Seeker / by Jen Viegas) — Adiël Klompmaker was struck by a similar idea a few years ago, when he was a postdoctoral researcher at the Florida Museum of Natural History. He was preparing a database of drill holes created by marine predators in shells, and it occurred to him that the shells had untapped potential as “smoking gun” evidence for over 500 million years of marine predator-prey interactions.
He and his colleagues have since conducted a detailed analysis of thousands of such shells, revealing that numerous marine predators have grown steadily larger and more powerful over time, while their preferred prey has remained relatively small.
The findings, reported in the journal Science, support what is known as the “escalation hypothesis.” This theory, in part, holds that increasingly powerful and metabolically active animals at the top of the food chain can drive evolutionary trends in their prey, such as by affecting their defensive arsenals and ability to move.
“There is a long-term increase throughout the last 500 million years in the size of drilling predators and predator-prey size ratios of drilling predators and their prey,” said Klompmaker, who is now a postdoctoral researcher at the University of California, Berkeley.
“Although prey size did not increase or decrease over the last 500 million years, they may have responded to their predators by becoming more mobile,” he added. “Some of them started to burrow into the bottom of the oceans, and some developed a more fortified shell.”