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Snail presumed extinct turns up again

Paul Johnson/Alabama Aquatic Biodiversity Center

This ScienceDaily piece, (June 3, 2011) “Mass Extinction Victim Survives: Snail Long Thought Extinct Isn’t” looks at a recent local extinction of snail species (limpets) of which, it turns out, there was a survivor:

… a major mass extinction took place in North America in the first half of the 20th century, when 47 species of mollusk disappeared after the watershed in which they lived was dammed.

Now, a population of one of those species — a freshwater limpet last seen more than 60 years ago and presumed extinct — has been found in a tributary of the heavily dammed Coosa River in Alabama’s Mobile River Basin. Researchers from the University of Michigan, the Alabama Aquatic Biodiversity Center and the Kentucky State Nature Preserves Commission reported the rediscovery May 31 in the online, open-access journal PLoS ONE.

They recognized the limpet (a snail with a cap-shaped shell) from museum collections.

“Their habitat was destroyed in huge chunks,” Ó Foighil said. The result: 47 of 139 endemic mollusk species were lost, representing a full one-third of all known freshwater mollusk extinctions worldwide.

Then, about 20 years ago, thanks to increased interest in and funding for conservation projects, biologists began searching patches of the drainage that weren’t affected by damming, trying to find remnants of the original, rich fauna and save whatever still could be saved.

Who knows, but if they scour the creeks, they’l find more.

One third of species believed recently extinct have turned up again. Sources suggest that extinction is usually a process, not an event. It may reverse itself before the end if remaining habitat can be found.

See also: Extinction: Another reason why biologists should study math

and Oldie but goodie: How to become extinct

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