Tracking Evidence of 'The Great Dying'

[Elmore Furth]

There is still a debate as to what precipitated the "Great Dying" 251 million years ago when 90% of species became extinct. It is agreed upon that there was massive vulcanism but as to whether this was caused by a meteorite is still debated.

New Evidence Says Earth’s Greatest Extinction Caused By Ancient Meteorite

The Siberian Traps represents one of the largest flood basalt provinces on Earth and erupted 251 million years ago over a time interval of about 900,000 years. The eruptions spewed 2-3 million cubic kilometers of basalt lava, covering 3.9 million square kilometers to a depth of 400 to 3000 meters. It was so large and violent that it could have caused worldwide atmospheric contamination by injecting vast amounts of dust and sulphate gases into the atmosphere. The world climate could have been affected with the addition of volcanic gasses in the atmosphere.





In May 2004 announcement was made that the Permian killer crater may indeed have been found. Marine geophysics surveys off the northwest coast of Australia turned up a distinct anomaly buried under shallow seas that was promising enough to drill two deep holes in search for oil (several impact craters have served as petroleum traps). A competing event, in some ways superior because of size, has been announced as a leading candidate of the Killer Crater. This - as yet unnamed - lies under 1.5 km of ice in Wilkes Land in the Antarctic.

Impact Craters

ScienceDaily (Oct. 29, 2010) — More than 251 million years ago, at the end of the Permian period, Earth almost became a lifeless planet. Around 90 percent of all living species disappeared then, in what scientists have called "The Great Dying."

Thomas J. Algeo, has spent much of the past decade investigating the chemical evidence buried in rocks formed during this major extinction. The University of Cincinnati professor of geology has worked with a team of scientific colleagues to understand the ancient catastrophe. Algeo will present his latest findings at the annual meeting of the Geological Society of America, Oct. 31 to Nov. 3, in Denver.

The world revealed by Algeo's research sounds horrific and alien -- a devastated landscape, barren of vegetation, scarred by erosion from showers of acid rain, huge "dead zones" in the oceans and runaway greenhouse gases leading to sizzling temperatures. This was Earth, 251 million years ago.


Tracking Evidence of 'The Great Dying'

[Yrger]

1. How do they come to the figure of 90% of all living species?

More than 251 million years ago, at the end of the Permian period, Earth almost became a lifeless planet. Around 90 percent of all living species disappeared then, in what scientists have called "The Great Dying."



So, the 10% of all living species surviving from 251 million years ago should by today reasonably be even less, unless the evolution program of nature has succeeded from random mutation and natural selection to have brought about more species, and we can intelligently now today say that there must be numerically more than just 10% of all the living species 251 million years back, what with the addition from the evolution program of nature by which new species come forth from previous species, as I said by the socalled steps in the program of random mutation and natural selection, namely, evolution.

Okay, what is the percentage today by a rough but still intelligent estimate now of living species compared numerically with the totality of living species 251 million years ago prior to the disappearance of 90% of the then totality of all living species?





Yrger

[muriel_volestrangler]

2. They count up the species in the fossil record just before the event, and the number just after

The number after is 10% of the one before; so 90% of species died out.

It's not comparing the number of species then and now. That's a comparison you can't really do, because counting the total number of species then by fossil and those now by observation of living plants and animals isn't the same process. Even comparing the fossil record of, say, 1 million years ago and the Permian wouldn't be valid - in 251 million years, rocks can get eroded and fossils destroyed. There may be species from back then that we'll never know about, because all fossils of them were destroyed in later eras. You can say the chances of those from 250 and 252 million years ago being lost are about the same, so you can compare the number of species over 2 close times like that.

However you say: "the 10% of all living species surviving from 251 million years ago should by today reasonably be even less, unless ..."

Many more species have indeed appeared in the intervening 251 million years. But evolution is not a 'program' as you term it, not does it 'succeed' or fail. It just happens.

[14thColony]

3. Species seek to survive and reproduce, by any means possible

With 90% of species gone on a planet still just as big as now, that's suddenly a whole lot of empty living space for the surviving species to colonize (move into). And as they moved into new ecological settings, natural selection would begin to apply pressure on them to adapt to the new setting. Only species perfectly matched to their environments stop (relatively) evolving, but that's very rare. Since most environments are constantly changing (relatively), most species are under constant adaptive pressures, expressed via natural selection -- those better adapted pass on there genes, those less adapted don't. Over time this causes that group of animals or plants in that new environment to evolve to the point they are no longer either willing or able to interbreed with the original group they came from, and a new species has come to be.

With so much empty space to move into, I'd hazard to guess the adaptive pressure, and therefore the rate of change, and therefore the rate of speciation was so great that it was a veritable explosion of new species. Just look what happened to mammals after the dinosaurs were no longer filling up all the prime ecological real estate: in a veritable blink of an eye mammals went from a few dozen known species the size of mice to hundreds of thousands of species, some the size of houses. And all because there were new niches suddenly open for colonization.

"Okay, what is the percentage today by a rough but still intelligent estimate now of living species compared numerically with the totality of living species 251 million years ago prior to the disappearance of 90% of the then totality of all living species?"

Uh...I...what? Well...as a percentage...there were 100% of species back then and there are 100% of species today... but somehow I don't think that's what you're trying to ask. As Muriel says, probably not measurable to any degree of accuracy. Hell, we don't even have a half-way decent estimate for the number of species on earth today, and we're here!