ShareThis Page
Nation

Microbe implicted in worst mass extinction

| Tuesday, April 1, 2014, 7:57 p.m.
A fossil remnant of a trilobite, a horseshoe crab-like creature, records part of the species’ survival the in the seas for hundreds of millions of years before becoming one of many animals wiped out in a mass extinction that befell the planet 252 million years ago.
Reuters
A fossil remnant of a trilobite, a horseshoe crab-like creature, records part of the species’ survival the in the seas for hundreds of millions of years before becoming one of many animals wiped out in a mass extinction that befell the planet 252 million years ago.

WASHINGTON — Sometimes bad things come in small packages.

A microbe that spewed humongous amounts of methane into Earth's atmosphere triggered a global catastrophe 252 million years ago that wiped out upward of 90 percent of marine species and 70 percent of land vertebrates.

That's the hypothesis offered by researchers aiming to solve one of science's enduring mysteries: what happened at the end of the Permian period to cause the worst of the five mass extinctions in Earth's history.

The scale of this calamity made the one that doomed the dinosaurs 65 million years ago — a 6-mile-wide asteroid smacking the planet — seem like a picnic.

The implicated microbe, Methanosarcina, is a member of a kingdom of single-celled organisms distinct from bacteria called archaea that lack a nucleus and other usual cell structures.

“I would say that the end-Permian extinction is the closest animal life has ever come to being totally wiped out, and it may have come pretty close,” said Massachusetts Institute of Technology biologist Greg Fournier, one of the researchers.

“Many, if not most, of the surviving groups of organisms barely hung on, with only a few species making it through, many probably by chance,” Fournier added.

Previous ideas proposed for the Permian extinction include an asteroid and large-scale volcanism. But these researchers suggest a microscope would be needed to find the actual culprit.

Methanosarcina grew in a frenzy in the seas, disgorging huge quantities of methane into Earth's atmosphere, they said.

This dramatically heated up the climate and fundamentally altered the chemistry of the oceans by driving up acid levels, causing unlivable conditions for many species, they added.

The horseshoe crab-like trilobites and the sea scorpions — denizens of the seas for hundreds of millions of years — simply vanished. Other marine groups barely avoided oblivion including common creatures called ammonites with tentacles and a shell.

On land, most of the dominant mammal-like reptiles died, with the exception of a handful of lineages including the ones that were the ancestors of modern mammals including people.

“Land vertebrates took as long as 30 million years to reach the same levels of biodiversity as before the extinction, and afterwards life in the oceans and on land was radically changed, dominated by very different groups of animals,” Fournier said.

The first dinosaurs appeared 20 million years after the Permian mass extinction.

TribLIVE commenting policy

You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.

We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.

While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.

We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers

We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.

We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.

We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.

We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.

click me