Recovering From A Mass Extinction

Science Daily ^ | 1-20-2008 | University of Bristol.

[blam]

Recovering From A Mass Extinction

Fossilised skull of the sabre-toothed Lycaenops, a top predator of the latest Permian. (Credit: Photo by Michael Benton)

ScienceDaily (Jan. 20, 2008) — The full recovery of ecological systems, following the most devastating extinction event of all time, took at least 30 million years, according to new research from the University of Bristol.

About 250 million years ago, at the end of the Permian, a major extinction event killed over 90 per cent of life on earth, including insects, plants, marine animals, amphibians, and reptiles. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. This was the nearest life ever came to being completely wiped out.

Previous work indicates that life bounced back quite quickly, but this was mostly in the form of ‘disaster taxa’ (opportunistic organisms that filled the empty ecospace left behind by the extinction), such as the hardy Lystrosaurus, a barrel-chested herbivorous animal, about the size of a pig.

The most recent research, conducted by Sarda Sahney and Professor Michael Benton at the University of Bristol and recently published in Proceedings of the Royal Society B, indicates that specialised animals forming complex ecosystems, with high biodiversity, complex food webs and a variety of niches, took much longer to recover.

Sahney said: “Our research shows that after a major ecological crisis, recovery takes a very long time. So although we have not yet witnessed anything like the level of the extinction that occurred at the end of the Permian, we should nevertheless bear in mind that ecosystems take a very long time to fully recover.”

Sahney and Benton looked at the recovery of tetrapods – animals with a backbone and four legs, such as amphibians and reptiles – and found that although globally tetrapods appeared to recover quickly, the dramatic restructuring that occurred at the community level was not permanent and communities did not recover numerically or ecologically until about 30 million years later.

Professor Benton explained: “Diversity is most commonly assessed by tallying the number of taxa on a global scale, but these studies are subject to the vagaries of sampling. By examining well-preserved and well-studied faunas, the taxonomic and ecological recovery of communities after the Permian extinction event can be examined more accurately, and the problems of geological bias are largely avoided.”

The Permian extinctions occurred in three waves, the largest being at the boundary between the Permian and Triassic periods, 251 million years ago. This was the most devastating ecological event of all time, thought to be caused by large-scale volcanism in Russia which produced the ‘Siberian Traps’, covering over 200,000 square kilometers (77,000 square miles) in lava.

Adapted from materials provided by University of Bristol.

[gleeaikin]

I have always though that the Siberian Trapps may have flowed out of a giant meteor strike. I also had the same thought about the Deccan Trapps in India which were built at the time of the dinosaur extinction. There is some talk of a 400 by 600 mile?/km? crater in that area known as the Shiva crater.

[SunkenCiv]

Barren Siberia, Of All Places, May Be Original Home To Animal Life
Science News
adapted from materials by Univ of Florida
Thursday, April 8, 2004

UF's Joe Meert and KU's Bruce Lieberman concluded that precursors to modern continents began splitting off from a giant supercontinent at the South Pole about 580 million years ago, migrating north toward the equator for about 80 million years. The scientists' analysis suggests that a prominent theory holding that the continents moved far more rapidly is wrong. It also suggests that trilobites, the long-ago forbearers of crabs and lobsters, originated in present-day Siberia when it was a separate continent from Asia and located much farther south... Working independently, the UF and KU geologists each determined that the southern supercontinent began breaking up around 580 million years ago. The separate continents drifted northward toward the equator at about six inches per year, with this relatively rapid movement ending about 500 million years ago, they found... While six inches is fast by comparison to today's continental movement of speed of one to two inches per year, it is far slower than that proposed by another prominent theory on early continental movement. That theory, known to scientists as "inertial interchange true polar wander," held the continents rotated from the South Pole to the equator in a mere 15 million years from 523 million to 505 million years ago - meaning they moved at more than 25 inches per year - more than four times faster than what Lieberman and Meert found.