Ungulate Fossil Found in India

As if hidden from the paleo tooth fairy, a lone molar belonging to a hoofed mammal stayed tucked beneath a pillow of volcanic rock in central India for more than 65 million years. Recently uncovered, the tooth predates similar fossils found across the globe.

The dental discovery sheds light on the evolution of adaptations that allowed a group of mammals called ungulates to thrive as expert grazers. It also suggests, according to newly published research on the tooth, that the Indian subcontinent could be the point of origin of many groups of mammals.

The lower right molar, about half the size of an ant (2.5 millimeters long), was found embedded in central India's Deccan volcanic flows. The researchers estimate the tooth dates back to the late Cretaceous period (144 million to 65 million years ago), a time when India was not connected with other continents and dinosaurs still walked the Earth.

The fossil belonged to a new species of ungulate dubbed Kharmerungulatum vanvaleni, a hoofed animal related to modern horses, cows, pigs, sheep and deer. And it represents the oldest known evidence for the so-called archaic ungulates (small, primitive hoofed mammals), predating by millions of years the explosion of mammalian life that occurred during Paleocene Epoch, from 65 million to nearly 55 million years ago.

"Until now, the known fossil record of [the] oldest archaic ungulates or supposed ancestors of living ungulates comes from the Early Paleocene of North America," Guntupalli Prasad of the University of Jammu in India told LiveScience. He is the lead author of the tooth study, detailed in the Nov. 9 issue of the journal Science.

So the ungulates survived on the Indian subcontinent throught he Deccan Traps to the current day. huh. Very, very deadly that eruption.

Bio Evidence for TJ Extinction

The authors note that "the release of CO2 from the outgassing of a large volume of basaltic lava has been cited as triggering an interval of intense greenhouse warming that resulted in a mass extinction at the Triassic-Jurassic boundary (200 million years ago)," citing the studies of Yapp and Poths (1996), McElwain et al. (1999) and McHone (2003), and they write that "similar transient increases in paleo-pCO2 have been identified at other important paleontologic boundaries using fossil stomatal data, including the Permian-Triassic (250 million years ago) and the Cretaceous-Tertiary (65 million years ago)," citing the work of Retallack (2001) and Beerling et al. (2002). However, they report that in addition to releasing CO2 into the air, "large flood basalt eruptions may include the loading of the atmosphere with SO2," which could also produce mass extinctions. Hence, they decided to collect a set of real-world measurements designed to determine if elevated concentrations of atmospheric SO2 can lower plant stomatal index in the same way that elevated concentrations of CO2 do, which if found to be the case would imply that calculations of pCO2 based on the stomatal frequency of fossil leaves may actually be due in large part to SO2, implying lower concentrations of atmospheric CO2 during past mass extinction events, which would imply less intense greenhouse warming and possibly reveal SO2 to be the primary culprit behind the mass die-offs.

[...]

Tanner et al. measured the stomatal index (SI) of the common swordfern (Nephrolepis exaltata) in various plumes of actively outgassing vents of Kilauea, a basaltic shield volcano on the southeastern flank of Hawaii, as well as in other locations chosen in such a way as to provide situations where CO2 was high and SO2 low, where CO2 was low and SO2 high, and where both CO2 and SO2 were either high or low together.

[...]


Tanner et al. conclude that "long-term eruptions may have produced a similar phenotypic response in plant species across large areas of the globe that is indistinguishable from that produced by elevated CO2." As a result, they further conclude that it is "necessary to examine more closely the impact of volcanogenic SO2 on the global environment and the potential role of SO2 outgassing as a mechanism of extinction."

hmmm. Interesting. Plants respond to SO2 similiarly as to elevated CO2. It would be interesting to see if there was a similar response among those critters that are supposed to be vulnerable to SO2 poisoning - like amphibians - to see if there was a die back at the same time. If not there might be a small issue here. Or it might be a way to differentiate the exact mechanism between CO2 and SO2 from flood basalts.

Stop Dreaming! The KT is NOT the PT!

Alpha: In the Beginning

This is not the original post that I wanted to write. I wanted to specifically cover my rant on YAGUMETs. Or as the rest of you have seen me call them 'Yet Another Grand Unified Mass Extinction Theory', but in the plural. However, since Dr Keller - ever the anti-bollide guerrilla - sent out yet another press release in support of vulcanism as the culprit for the KT Mass Extinction killer, I thought I would shift gears and try to do a comparison of the PT Extinction and KT Extinction events to try to make a point. Since Dr Keller favors vulcanism, I am going to make the assumption for this post that the Permian Extinction, which has been pretty strongly linked to the effects of massive vulcanism, is a 'proven' fact and its signature is the gold standard for vulcanism being the cause. Even though I am thoroughly convinced that the KT Extinction was caused by Chicxulub. I am going to assume we're unproven here and compare the evidence and signatures of the KT to the PT. I will return to the YAGUMETs post for my next big paleo post, but for now, let's get on with the show.


The Permian Extinction was not a pretty picture. I sketch it out here at least moderately well. It was almost certainly caused by the prolonged and quite nasty eruptions of the Siberian Traps, a truly terrifyingly large and prolonged flood basalt eruption. The evidence that supports this had a very distinctive signature: certain events happened and we think we know why. If we use this signature as a baseline for comparing other extinctions to the PT Extinction we really ought to be able to see if that other signature fits the same profile. If it does, then it seems very likely that the extinction was caused by the same mechanism. With that in mind, we'll approach and compare the KT to the PT!


Extinction Pulses

One of the very distinctive and confusing items about the PT Extinction was that it seemed like it was a very long term affair. This was because careful collections and biostratigraphy had not been done until relatively recently. The reason for appearing to be a very drawn out affair was there were actually multiple pulses of mass death. The pattern of pulses looks something like a drum beat that gets louder and fades. In fact, the last pulses take place actually after most of the dying took place and end up geochronologically in the Triassic[1]. It's very, very distinctive and almost certainly a result of the eruptions and their resultant ecological complications tripping past some thresholds. The the multi-pulse extinction attribute seems to be a very important one for vulcanism caused extinctions and makes perfect sense given how it kills. How does this compare to the KT Event's pattern of extinction? The fact of the matter is that it doesn't match at all. There seems to have been a minor mass extinction ten million years prior to the KT Boundary, but it does not seem to have reduced the number of dinosaur genera present and even had the effect of the mammals diversifying. That might be argued that the prior minor extinction might be the first pulse of the KT, but...there's no subsequent pulses into the Cenozoic! The KT Extinction was a quick and bloody affair: there appears to be only a single pulse involved.


Biotic Recovery

The Permian Extinction killed a lot of everything. By some counts as much as 90% of everything died. That included plants, animals, etc. As a result, and also as a consequence of what was changed environmentally because the the Siberian Traps, life took a very long time to recover. There were sections that have no fossils at all. While the extinction was less nasty in the terrestrial environment - approximately 70% of everything died there - beds of the Karoo in South Africa, one of the best places for chronologically uninterrupted PT Event sections, there are no fossils at all for over 5 million years. Life would not recovery the diversity of the Late Permian for a very long time. Delayed biotic recovery would be another good attribute for identifying vulcanism induced extinctions. The KT Extinction had, at the most, a 300k year recovery period. For something that killed 70% of everything, this is remarkably fast and completely unlike the PT Event. The diversity of life would increase very, very fast after the KT Event. This would also lean towards the idea that the KT Extinction had a different mechanism for the root cause.



Climatic Changes

During the PT Event, it appears that the Siberian Traps belched tons of carbon dioxide. This caused a massive upswing in temperature especially with the addition of the forcing caused by methane as well. The upswing appears to have been in the ten Celsius range. While the temperature dropped down, it remained high throughout the Triassic and into the Jurassic. This is supported by the isotope measurements and mineral deposits. On the other hand, the climate that crosses the KT Boundary as geologically recorded seems to be pretty stable. It was warm and stayed warm. There doesn't seem to have been a wild change over a prolonged period as it was with the PT Extinction.



Differences in Marine Biotic Extinctions

One of the most profound differences in the KT and PT Extinctions can be found in what died first and what was most effected in the oceans. During the PT Extinction, the benthic organisms - those that live on the seabed - were effected first AND most severely. As you rose up from the depths of the sea, the extinction got less and less severe - though, truthfully, that's something of a hair's difference, the PT Extinction was just damnably horrible - until you reached the terrestrial environment where it was the least severe. The key point though here is that the benthic environment & ecology was mopped across the floor. The reason for this is that the oxygen level dropped down to a anoxic state and full of hydrogen sulfide: the chemical analyses of the PT sediments support this. The KT Extinction couldn't be more different. The organisms effected the most were those that were those that were living in the euphotic zone: photoplankton, ammonites, the great marine reptiles, etc. The benthic organisms were far less impacted. This is a VERY strong indication that something different happened at each extinction event.


Extinctions in the Terrestrial Realm

In the terrestrial environment the Permian Event seems to have been a little uncertain as to what allowed organisms to survive the Great Dying. Truthfully, not enough research has gone into trying to find some sort of common theme that might unite what survived and what did not here. From the point of view of what is currently known, there is no common theme. It appears currently that the killing didn't favor one type of organism over another. This would be what Raup called a 'Field of Bullets' scenario. It truly remains to be seen though. On the other hand, it appears that at least for KT Event this was rather different. There was a definite pattern involved. At first it was thought that it was a weight limit: no more than 50 kg survived the KT Extinction. That hasn't quite turned out to be true: the cut off wasn't mass or weight, but metabolic requirements. Rather it was a metabolic requirement. If your required more calories than a certain amount - the exact amount uncertain right now - then you got whacked for sure. The prime example of this is the Sebecosuchidae, a form of Mesosuchia (or Mesoeucrocodylia, if you're more accurate). the Sebecosuchidaes were largish terrestrial carnivores that made the cross-over from the Mesozoic to the Cenozoic. IIRC, they were over 6m in length (Darren Naish has an excellent article on the subject at Tetrapod Zoology). This means that there is a definite and solid pattern. The KT Extinction was more selective in what died than the PT Extinction. However, there was still an element of randomness to the groups that were within the surviving criteria; frex, 50% of mammals died out and they were well within the metabolic requirements for survival. Lady Luck still had her due. However, this is still very different than in the PT Extinction as far as the research so far has indicated.

Omega: In the End
Now, I have run out of time. I hope that by detailing some of the differences between the KT Mass Extinction and the PT Mass Extinction. I have tried to avoid the usual arguing points: evidence of impact, charcoal traces, geochronology of the Deccan Traps, etc. I have been trying to point out the other diagnostic characteristics that are often overlooked. The fact of the matter is that these two extinctions killed in very different ways. These two extinctions effected organisms of different types. They cannot be caused by the same mechanism. Extinction events are not just something that has a geochronologically convenient 'explanation.' That explanation has to fit the pattern of that extinction as well as the time frame.


I will do a detailed KT Mass Extinction post in the relatively near future, but that will come after the YAGUMETs post. Now let's see if anyone comes along and beats me with a big stick.


1. Which makes me wonder why it's, well, the Triassic if we are defining the extinction event as the demarker, but I am not a geologist.

More Support for Vulcanism Causing PT Extinction

The greatest mass extinction in Earth’s history also may have been one of the slowest, according to a study that casts further doubt on the extinction-by-meteor theory.

Creeping environmental stress fueled by volcanic eruptions and global warming was the likely cause of the Great Dying 250 million years ago, said USC doctoral student Catherine Powers.

Writing in the November issue of the journal Geology, Powers and her adviser David Bottjer, professor of earth sciences at USC, describe a slow decline in the diversity of some common marine organisms.

The decline began millions of years before the disappearance of 90 percent of Earth’s species at the end of the Permian era, Powers shows in her study.

More damaging to the meteor theory, the study finds that organisms in the deep ocean started dying first, followed by those on ocean shelves and reefs, and finally those living near shore.

“Something has to be coming from the deep ocean,” Powers said. “Something has to be coming up the water column and killing these organisms.”

That something probably was hydrogen sulfide, according to Powers, who cited studies from the University of Washington, Pennsylvania State University, the University of Arizona and the Bottjer laboratory at USC.

Those studies, combined with the new data from Powers and Bottjer, support a model that attributes the extinction to enormous volcanic eruptions that released carbon dioxide and methane, triggering rapid global warming.

The warmer ocean water would have lost some of its ability to retain oxygen, allowing water rich in hydrogen sulfide to well up from the deep (the gas comes from anaerobic bacteria at the bottom of the ocean).

If large amounts of hydrogen sulfide escaped into the atmosphere, the gas would have killed most forms of life and also damaged the ozone shield, increasing the level of harmful ultraviolet radiation reaching the planet’s surface.

Powers and others believe that the same deadly sequence repeated itself for another major extinction 200 million years ago, at the end of the Triassic era.

I blogged about the PT Extinction and the Late Triassic Extinction before. This seems to be further support for the conclusions drawn.

Toba Overblown?

The stone tools were found both above and below a layer of ash left behind by a volcanic "supereruption" 74,000 years ago. The discovery hints that humans in the region survived the blast's devastating effects.

Strike N for Baxter et al.

NorAtlantic Volcanic Origins of the PETM

Scientists examining a spike in worldwide ocean temperatures 55 million years ago have linked it to massive volcanic eruptions that pushed Greenland and northwest Europe apart to create the North Atlantic Ocean.

Writing in the journal Science, geologists at Roskilde University in Denmark, Oregon State University and Rutgers, The State University of New Jersey, present evidence that this intense volcanic activity occurred at the same time ocean temperatures jumped five to six degrees Celsius. A better understanding of previous global warming episodes will give scientists perspective as they study today's climate and ocean level changes pegged to human generation of greenhouse gases.

"That prehistoric volcanic activity released more than 2000 gigatonnes (billion metric tons) of carbon into the oceans and atmosphere in the form of methane and carbon dioxide – two potent greenhouse gases," said Michael Storey of Roskilde University in Denmark, the study's lead author. "The carbon probably came from the heating of earlier deposits of decayed organic matter – similar to deposits in the Atlantic and North Sea we tap today for oil and gas."

Consistent with the Late Permian-Siberian Traps theory too.