Monday, February 24, 2014

Earth's Greatest Extinction Hardly Changed Ocean Ways of Life

Gastropod (snail) fossils 

Gastropods (snails) (Coelostylina werfensis and ‘Polygyrina’ gracilior) from the Early Triassic representing slow-moving, epifaunal grazers.

 Earth's largest mass extinction had surprisingly little effect on the range of lifestyles seen on the planet's seafloor, despite the loss of more than 90 percent of marine species, researchers find.

Understanding the impacts of this ancient extinction event may shed light on the damage climate change might now inflict on the planet, the scientists say.

The end-Permian mass extinction, which occurred 252 million years ago, was the biggest die-off in the planet's history, and the largest of the five mass extinctions seen in the fossil record. The cataclysm killed as much as 95 percent of all species on Earth. [Wipe Out: History's Most Mysterious Extinctions]

Mass extinctions are often followed by an explosion in diversity, as survivors evolve to fill the niches or roles that dead groups of life once held in their communities. For instance, after the end-Permian die-off, the predecessors of modern burrowing clams, grazing and carnivorous snails, and predatory crustaceans emerged.

However, the overall impact of the end-Permian die-off on marine ecosystems was uncertain. To find out more, scientists analyzed fossils of all known groups of seafloor invertebrates from the periods before and after the mass extinction — the Permian and Triassic periods, respectively.

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