From the UNIVERSITY OF BRISTOL
Life on land and tropical overheating 250 million years ago
One of the key effects of the end-Permian mass extinction, 252 million years ago, was rapid heating of tropical waters and atmospheres.
How this affected life on land has been uncertain until now.
In a new study published today, Dr Massimo Bernardi and Professor Mike Benton from the School of Earth Sciences at the University of Bristol show how early reptiles were expelled from the tropics.
Massimo Bernardi 2018
Geologists had already shown that ocean temperatures rose by 10-15 degrees centigrade as a result of global warming triggered by massive volcanic eruption.
The huge volcanoes erupting in Siberia belched thousands of tonnes of carbon dioxide into the atmosphere, setting off a chain reaction that involved global warming, acid rain, and loss of oxygen from the sea bed.
Together, these environmental crises led to the death of 95 percent of species.
Ten main lines of reptiles survived the crisis and re-populated the Earth in the subsequent Early Triassic time. However, they avoided the tropics, as did fishes and other animals in the oceans. The tropical clear-out was understood to have lasted several million years, but the new work shows that is not the case.
Dr Bernardi, the lead author, now Curator for Palaeontology at MUSE Science Museum in Trento, northern Italy, said: “We thought of using all available data to make our study as comprehensive as possible.
“Up to now, people used only the skeletons of the early reptiles from before and after the crisis, but these are found only in Russia and South Africa, so it is impossible to document any latitudinal shifts.
“We had been building a huge database integrating both skeletal and footprint data, and this allowed to fill a lot of the gaps, over Europe and North America for example.”
Co-author, Professor Benton, added: “Our analyses show that the land reptiles moved north by 10 or 15 degrees to escape the tropical heat.
“The footprint and skeleton data agree in this, but we had to consider how the geographic distributions of fossils matched available land masses and the availability of rock. After all kinds of checking for possible errors, we are clear this is a real effect.”
As the turmoil in the Early Triassic settled down, reptiles moved back to the tropics, but also maintained their temperate faunas. The turmoil then had a stimulating effect, and many new groups came on the scene, including the first dinosaurs.
Dr Bernardi said: “This was an important time in the history of life. It marks the end of ancient kinds of animals in the oceans and on land, and the beginning of the modern-style faunas we see today.
“What we have done is to try to dig deeper into our understanding of the exact consequences of rapid global warming during a well-documented historical event. This might be helpful in understanding what might happen in the future as we undergo more global warming today.”
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If one is thinking about an anti-podal asteroid impact point causing the Siberian Traps volcanoes, first you have to go back to the geography that existed at that time.
The Siberian Traps region was about where Finland is today. Antipodal to where Finland is today would be about where New Zealand is today.
But New Zealand was attached to Pangea on its southeast side at that time and then moved to the south pole and then moved back out into the Pacific starting 80 million years ago. So New Zealand has overridden the previous place that was anti-podal to the Siberian Traps at the volcanic activity timeline.
But then, the Pacific ocean plate that New Zealand has overridden has also been moving since that time. It is moving north-west. The exact location that would have been the actual impact site 250 million years ago is probably very close to between the Philippines and Indonesia now.
Anybody see a giant crater on the Pacific floor between the Philippines and Indonesia?
BI,
The angle of the impact would have a big influence on the resultanting
concentration of force.
Impacts that large don’t leave craters.
Sure they do. This is the biggest impact crater that we know about – Vredefort in South Africa from a 10 km asteroid strike 2.0 billion years ago.
There is no sea-floor that old anywhere in the World, so a deep-ocean impact would long ago have been subducted. As a matter of fact it is the absence of an 250 ma old seafloor that makes all this wild guessing possible, since there are no good continuous, undisturbed deposits that span the citical interval.
By the way there is evidence for a large impact at about the right time at Graphite Peak in Antarctica, but no crater (except the hypothetical Wilkes land structure).
Would someone please turn down the sensationalist science reporting.
Yeah, that’d be nice, wouldn’t it? But if the They (Warmians, CAGWers, Greenbeans) aren’t allowed to shout, jump and down and point, and do other silly things, the more reasoning souls won’t have any way to refute them. Think how much stuff has been pulled up to public scrutiny now, to refute the pseudo-ideological twaddle and show it for what it is – a money grab?
“The availability of rock”
Western North America was a desert like the Sahara in the late Permian. We see it in the Kiabab, De Chelly, White Rim, and Park City sandstones. All this was 5-10 degrees N latitude. Certainly not surprising there would be an exodus, and not good for preserving tracks.
Far from being grouped at the equator, the continents were meridional with a modest equatorial waist band extending from western North America to North Africa.
The availability of mud is more relevant for the preservation of tracks and fossils.
The Earth’s surface is roughly 70% water and the question arises: where did it come from? I suspect the mantle. But that water is also very salty, so where did all that chlorine come from?
What seems to be the current agreed upon theory is that the water came from comets and asteroids during the late heavy bombardment phase.
The sodium and chloride were leached from the rocks over the last 4 billion years or so.
The Earth’s surface is roughly 70% water and the question arises: where did it come from? I suspect the mantle. But that water is also very salty, so where did all that chlorine come from?
Is there any other ‘volcanic eruption’ that causes warming, anywhere? I can’t imagine Dr Massimo Bernardi and Professor Mike Benton being the first to discover ‘volcanic eruption’ cause warming not cooling.
I think volcanoes were not involved. The great eruptions that created the Steps and Deccan Traps, and the great flows that buried Washington, Oregon, and California were massive tears in the earth, not the snow blanketed tourist havens we see along the ring of fire today.
I think they have forgotten one of the most basic rules of Paleontology: “Absence of evidence is not evidence of absence”.
By their reasoning e. g. dinosaurs went extinct more than once. There are several intervals during the Mesozoic lasting as much as a million years from which there is not a single dinosaur fossil known from anywhere in the World.
It is interesting to compare with the latest Maastrichtian, the time immediately before the K-Pg extinction and see how widespread dinosaur fossils are. Remember that this is a much more recenrt epoch with a vastly better fossil record, that has been intensively studied.
So of course we have world-wide data for where dinosaurs occurred just before the big extinction? Well, not exactly. What we have is mostly the Hell Creek formation in Montana and the Dakotas. There are practically no latest Maastrichtian dinosaurs from anywhere else in the World. There may be a few in New Mexico, but the dating is shaky, and some more in Southern China, but the dating is very shaky there.
Jeff in Calgary January 11, 2018 at 8:15 am said:
“…I thought recent CONSENSUS science was that that extinction was caused by a meteor…”
You may be thinking of the Dinosaur extinction of 65 million years ago.
I just watched a program on CBC ICI Explora about two expeditions to Tunguska, Siberia, trying to prove competing explanations for the explosion of 1908.
The group from Italy adhered to the generally held view, that an extraterrestrial body exploded 11km above the spot, explaining the tree trunks still standing at ground zero, while all the forest around was flattened outward. Their contribution brought some previously unknown mystery to the explanation though, in the form of a crater shaped lake nearby which appears to have been formed at the same time. The preliminary suggestion was that part of the asteroid or meteorite broke off and hit the ground instead of vapourizing.
The American group was trying to prove that the 1908 event was caused by a minor “verneshot” incident occurring at the place where a huge vernshot occurred 250 million year previous causing the mass extinction of that era. The proof they were looking for was shocked quartz, and apparently they found it, in the form of a large boulder of sandstone on the peak of a small mountain of basalt. How this relates to the telephone post
trees was not explained. Or perhaps I missed it, since my French is a bit shaky. But the explanation offered is that the boulder was shot out of a vent during the 1908 event from its previous location 800 meters below.
CO2 was nothing to so with the P-T extinction.
But Prof Benton’s finding of reptiles moving away from the equator to higher latitudes is important and makes sense.
When they say “the ocean got a lot hotter” do they have any idea what they are even saying? The vast ocean heat capacity means this is easier said than done. Even sustained volcanism would not be expected to raise global ocean temperature by 10 degrees. And CO2 doen not drive ocean temperatures but merely follows them as a proxy.
No – the clumping of land into a single roughly isometric continent would mean that the uninterrupted featureless ocean over the rest of the globe would probably have lacked any deep thermo-haline circulation (THC) such as we have today largely driven by meridional deep and surface currents in the meridionally bounded Atlantic ocean. A point may have been reached during the clumping of landmass that the weakening of ocean circulation caused two effects. One was a failure of poleward heat transport from the equator, so that ocean heat was stagnantly trapped around the equator. The second was that the seas became largely anoxic. It is known that the almost total extinction of live in the ocean at the end-Permian – 98-99% while on land extinction was 93-94% – is due to ocean anoxia. The sea surface changed from blue-green to brown-orange in colour, black below about 10m.
No more marine photosynthesis, so atmospheric oxygen level may have dipped significantly.
(Can anyone confirm whether decreased oxygen % in the atmosphere was a feature of the end Permian extinction?)
Living species in an ecosystem are linked by trophic links (eating and getting eaten) in a chaotic nonlinear network. A consequence of this is fractal scale instability. Put simply, one species extinction may have no effect on any other species. Another extinction may cause also the extinction of a species that predated on the extincted species, and perhaps a handful of other similar species. Occasionally, extinction of one species can set off a chain of hundreds or thousands of extinctions. Even more rarely such a chain of extinctions might attain the level of a mass extinction.
Although we habitually think of mass extinctions as needing a big physical stress to the planet and climate to set them off (and are politically and vacuously mandated to invent a CO2 event for this) the model of species extinctions based on the theory of nonlinear networks allows a mass extinction to happen spontaneously with no external stressor.
But the overall point is that the end Permian extinction was driven by ocean anoxia accompanied possibly by lowered atmospheric oxygen, starting in the sea and setting off a chain of extinctions on land.
Maybe I’m just nitpicking, but I doubt any slitherins packed up and moved anywhere. The zones of thrivation (coined in this very post) moved north and south, and reptiles already in or near those zones thrived and morphed. Those outside didn’t. Those on the margins did so-so.
Yes there was no “Reptile flow” climate migtration in the style of “The Day After Tomorrow”, these changes would have occurred incrementally over thousands of lizard generations.
This paper assumes that it was CO2 from the Siberian traps that caused the massive global warming of the end Permian, but they have no proof of this. Just as CO2 hasn’t been proven by the use of hard data to have caused the abrupt warming of the last three centuries of the 20th century, something else could have been the actual cause. The only reasonable choice here is chlorine and bromine in the form of HCl and HBr, which is emitted by non-explosive, basaltic volcanoes of the type that characterized the subaerial Siberian traps. These halogen hydrides are photodissociated on polar stratospheric clouds to produce monatomic chlorine and bromine, which destroy ozone catalytically until reaction with methane finally removes them from the stratosphere. The resulting thinning of the ozone shield allows an increased influx of solar UV-B radiation, which causes severe sunburn, genetic defects, and, surprise, surprise, global warming! This mechanism fits the modern temperature time series far better than CO2, and there’s no reason to suppose that it wasn’t equally effective 250 million years ago.