lpetrich
Contributor
Lilliput effect - after mass extinctions, the surviving species are often much smaller that many of their close relatives before the extinction.
Ancient mass extinction may have shrunk Earth's creatures | Science | AAAS
Body-size reduction in vertebrates following the end-Devonian mass extinction
After a Mass Extinction, Only the Small Survive - The New York Times
Ancient mass extinction may have shrunk Earth's creatures | Science | AAAS
This is the Hangenberg event at the end of the Devonian Period.About 360 million years ago, Earth's seas were filled with myriad fishes, including creatures the size of school buses. Then a mass extinction hit the Age of Fishes. It killed off most of the big guys, according to a new study, and effectively shrunk most vertebrate species to the size of a human forearm or smaller. The findings imply that our planet's next mass extinction—which some believe is already underway—could similarly shrivel any species that remain.
The ancient extinction happened about 359 million years ago, at the end of the Devonian Period. A 100,000-year-long cold spell triggered the growth of glaciers almost down to tropical latitudes, says Lauren Sallan, a paleobiologist at the University of Pennsylvania. Sea level fell substantially, wiping out much of the shallow-water habitat surrounding major landmasses. Because few creatures had yet moved onto land, many ecosystems were devastated. About 96% of the world's vertebrate species disappeared, making it one of Earth's five largest die-offs.
Body-size reduction in vertebrates following the end-Devonian mass extinction
After a Mass Extinction, Only the Small Survive - The New York Times
After the mass extinction 359 million years ago, the scientists found, vertebrates were smaller on average than before, and they stayed that way for the next 36 million years.
Peter J. Wagner, a curator of paleobiology at the Smithsonian Institution who was not involved in the study, said one of its strengths was the broad stretch of time it covered.
Previous studies were “more like snapshots of what things were like before and afterwards,” he said. “This study goes much further.” Dr. Wagner, who wrote a commentary in Science accompanying the new study, said the work was also important because it dissected the Lilliput Effect, examining trends in different groups of species.
Some groups simply stayed at the same diminished size during the Mississippian, while others steadily shrank. Sharks, for example, dwindled from over a yard long to about just a few inches. Our own tetrapod relatives shrank from the size of dogs to the size of cats or smaller.