From the AGU:
Global fires after the asteroid impact probably caused the K-Pg extinction
About 66 million years ago a mountain-sized asteroid hit what is now the Yucatan in Mexico at exactly the time of the Cretaceous-Paleogene (K-Pg) mass extinction. Evidence for the asteroid impact comes from sediments in the K-Pg boundary layer, but the details of the event, including what precisely caused the mass extinction, are still being debated.
Some scientists have hypothesized that since the ejecta from the impact would have heated up dramatically as it reentered the Earth’s atmosphere, the resulting infrared radiation from the upper atmosphere would have ignited fires around the globe and killed everything except those animals and plants that were sheltered underground or underwater.
Other scientists have challenged the global fire hypothesis on the basis of several lines of evidence, including absence of charcoal-which would be a sign of widespread fires-in the K-Pg boundary sediments. They also suggested that the soot observed in the debris layer actually originated from the impact site itself, not from widespread fires caused by reentering ejecta.
Robertson et al. show that the apparent lack of charcoal in the K-Pg boundary layer resulted from changes in sedimentation rates: When the charcoal data are corrected for the known changes in sedimentation rates, they exhibit an excess of charcoal, not a deficiency. They also show that the mass of soot that could have been released from the impact site itself is far too small to account for the observed soot in the K-Pg layer. In addition, they argue that since the physical models show that the radiant energy reaching the ground from the reentering ejecta would be sufficient to ignite tinder, it would thereby spark widespread fires. The authors also review other evidence for and against the firestorm hypothesis and conclude that all of the data can be explained in ways that are consistent with widespread fires.
Source:
Journal of Geophysical Research-Planets, doi:10.1002/jgrg.20018, 2013
http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20018/abstract
Title:
K/Pg extinction: Reevaluation of the heat/fire hypothesis
Authors:
Douglas S. Robertson: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA; William M. Lewis: Department of Ecology and Evolutionary Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA; Peter M. Sheehan: Department of Geology, Milwaukee Public Museum, Milwaukee, Wisconsin, USA; Owen B. Toon: Department of Atmospheric and Oceanic Sciences and Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA.
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PS: I also note that you failed to respond to this question: “If all MEEs have the same causes, namely “gravity pulses” & marine regression (which of course is not the case), why then did trilobites survive the Late Cambrian, end-Ordovician & Late Devonian extinctions, only to succumb in the end-Permian, & why did ammonites survive the Devonian, Permian & end-Triassic events, only to perish in the end-Cretaceous?”
@John Tillman,
Again, I have asked specific questions and you evade them. I’ll try once more in the hope you will answer them.
1.Explain why Enantiornithine B went extinct before Enantiornithine A. If the chart you linked to has an error, PROVE IT!
2. Explain why the sea level drop at the P-T interval resulted in sea levels lower than they are today base on the Wiki sea level chart linked to. Glaciation was absent in the former but present in the latter.
Regarding the survival of the nautilus and the ammonite at the K-T interval, I already explained that the two are significantly different structurally. For example, the siphuncle runs through the center of the septa while it runs along the ventral periphery of the ammonite. During the Cretaceous ammonites started to increase shell thickness, tubercles and more robust spines. The nautilus has a thicker shell extending its implosion depth. Read Peter Ward’s books which indirectly support the theory I support. Regarding the extinction of the ammonites at Zumaya where he could not find ammonite fossils at or just below the K-T boundary, he stated:
“ …at the end of the Cretaceous, Zumaya was in the deepest part of the basin, at depths too great to sustain many ammonites.”
Regarding the tribolites becoming extinct at the P-T transition, there are two reasons:
1. The rapid pulse of increasing surface gravity on Pangea which, if you read the pdf cited, is explained.
2. At this point in time, the massive drop in sea level with surface gravity still lower than it is today coupled with the warm sea level temperature, massive amounts of methane were released from the epicontinental seas (i.e., the hydrates were exposed to low water pressure and high sea water temperature). The delta 13C graphs support this. The Siberian Traps enhanced this process. This second condition was not present in the prior mass extinctions.
Staten-John says:
March 31, 2013 at 9:11 am
@John Tillman,
Again, I have asked specific questions and you evade them. I’ll try once more in the hope you will answer them.
1.Explain why Enantiornithine B went extinct before Enantiornithine A. If the chart you linked to has an error, PROVE IT!
******************************
As I pointed out, it’s easy to prove. Just read the article. They both went extinct at the same time. How lazy can you be?
***********************************
2. Explain why the sea level drop at the P-T interval resulted in sea levels lower than they are today base on the Wiki sea level chart linked to. Glaciation was absent in the former but present in the latter.
**************************************
Can you read? For the third time, I was talking about the Ordovician, not the Permian. The O/S falsifies your unfounded assertion about “all MEEs”, as does the Devonian.
*****************************************
Regarding the survival of the nautilus and the ammonite at the K-T interval, I already explained that the two are significantly different structurally. For example, the siphuncle runs through the center of the septa while it runs along the ventral periphery of the ammonite. During the Cretaceous ammonites started to increase shell thickness, tubercles and more robust spines. The nautilus has a thicker shell extending its implosion depth. Read Peter Ward’s books which indirectly support the theory I support. Regarding the extinction of the ammonites at Zumaya where he could not find ammonite fossils at or just below the K-T boundary, he stated:
“ …at the end of the Cretaceous, Zumaya was in the deepest part of the basin, at depths too great to sustain many ammonites.”
******************************************
Of course they’re different. Ammonites, like the mosasaurs that fed on them, inhabited shallow waters, contrary to your prior baseless assertions. Nautiloids lived deeper in the ocean, so were sheltered from the worst effects of the impact. Your drivel about gravity makes no sense at all, since the effect is scarcely measurable & in any case Pangaea had been breaking up for 135 million years by the K/T.
None of which verbiage answers the question, “Why didn’t ammonites go extinct in the Devonian, Permian or Triassic MEEs, if only gravity & regression are always to blame?
**********************************
Regarding the tribolites becoming extinct at the P-T transition, there are two reasons:
1. The rapid pulse of increasing surface gravity on Pangea which, if you read the pdf cited, is explained.
2. At this point in time, the massive drop in sea level with surface gravity still lower than it is today coupled with the warm sea level temperature, massive amounts of methane were released from the epicontinental seas (i.e., the hydrates were exposed to low water pressure and high sea water temperature). The delta 13C graphs support this. The Siberian Traps enhanced this process. This second condition was not present in the prior mass extinctions.
************************************************
Oh, so now it doesn’t take just gravity & regression, but also volcanism. How about bolide impacts? They never have any affect in your cockamamie scheme?
How does a “pulse” of gravity work on a supercontinent forming over hundreds of millions of years & staying conjoined for on the order of 100 million years? It is to laugh.
BTW, you mean P-Tr, not P-T.
Why don’t you ask Peter Ward what he thinks about your anti-scientific fantasy? That should be educational for you & amusing for others.
ward.biology.uw@gmail.com
Argon/argon dating provides the smoking planet (even without global fires).
http://www.sciencemag.org/content/339/6120/684
Coincidence & correlation don’t always equal causation, but in a scenario as plausible as this, with so many effects directly attributable to a bolide impact, it would be perverse not to consider the case closed pending further evidence or interpretation.
BTW, if the Siberian Traps could contribute to the P/Tr MEE, then why not similar volcanism at the Tr/J & K/Pg events, Staten-John, not to mention the impact in the latter case?
Staten-John says:
March 30, 2013 at 6:37 pm
bla bla bla … 50% … bla bla bla
Sorry John, there is no math in your answer.
If you want to get knowledge why it happened you can read here:
http://agadorie.wordpress.com/2013/01/28/the-second-truth/
@John Tillman,
Again, I have asked specific questions and you evade them. I’ll try once more in the hope you will answer them.
1.Explain why Enantiornithine B went extinct before Enantiornithine A. If the chart you linked to has an error, PROVE IT! If it is an error post a quote from the website associated with the chart you provided a link to. How lazy can you be?
2.Explain why the sea level drop at the P-T interval resulted in sea levels lower than they are today base on the Wiki sea level chart linked to. Glaciation was absent in the former but present in the latter. This question was asked because you cited glaciation as the cause of the massive regression in prior mass extinction events. Since glaciation didn’t cause the massive regression at the P-T (yes that’s the Permian-Triassic) transition why do you insist it did at earlier mass extinctions?
What kind of logic do you use……how does my statement falsify anything?
Your comments about ammonites and nautiloids show your lack of knowledge. They both rise to the surface at night. Therefore the impact could not have affected one and not the other.
Pangea broke up at an insignificant rate (of separation) for most of the Mesozoic. You obviously don’t know anything about how angular momentum works otherwise you would not have made this statement. The continents don’t have to be attached to each other to affect angular momentum; it is their total latitudinal movement that’s important. If you don’t know basic physics you will never understand the theory.
You wrote in response to my explanation of why the tribolites went extinct due to the combined effects of higher surface gravity and the release of methane from the frozen hydrates at the sea floor:
“Oh, so now it doesn’t take just gravity & regression, but also volcanism. How about bolide impacts? They never have any affect in your cockamamie scheme?”
Clearly you have a reading comprehension problem.
Your insistence that the K-T extinctions were the result of an asteroid impact forces me to ask you a question (which I hope you don’t try to evade):
Would you be affected, either economically or otherwise, if the asteroid impact theory
is definitively proved wrong? Have you published any work that supports that theory?
Staten-John says:
Please try to think about it. Moving the core around would only influence surface gravity by a few percent.
The difference in mass between the core and other parts of the planet just aren’t that great. Regardless, where does the energy come from that is going to move the core away from the center? Any movement away from the center of the earth is by definition, moving uphill.
“birds has tens of thousand of years to evolve flight compensation for differences in air pressure.”
The sea creatures had the same amount of time to adapt.
george e. smith says:
March 28, 2013 at 4:10 pm
The impact will create a shock wave that will blast a hole in the atmosphere in all directions for hundreds of miles.
John Tillman says:
March 29, 2013 at 8:30 am
The lower level of O2 detected in the early Paleocene does however suggest at least regional firestorms.
—
Rotting vegetation would also consume oxygen and with much of the plant life killed off, it would take a long time to replace that oxygen.
No, the smaller pterosaurs were driven to extinction because an increasing surface gravity mandated that they increase their wing area to body mass ratio. The only way they could do that was to also increase their body size.
Higher gravity also means denser air.
The need to increase surface area would have been minimal.
MarkW,
Please don’t misquote me, I didn’t make that statement about birds and air pressure.
If you want to know what force it took to move the core elements (all three of them), study the conservation of angular momentum. Specifically what happens when Pangea (in whole or broken up) moves to higher latitudes.
Higher gravity does mean denser air but since at the time we are considering, surface gravity was lower than it is today, therefore the air density was also lower than it is today.
Staten-John:
I have evaded nothing. I have repeatedly provided all that a sane person of normal intelligence would need. You have ignored everything dispositive of your fantasy.
1) Read the article. It’s short, so that even with a challenged attention span, you should be able to handle it. The whole point is that all the species discussed survived to within 300,000 years of the K/T event. ALL includes both Enantiornithes A & B. Read it, then get back to me. I’ve provided you the link at least twice. Here it is again:
http://www.pnas.org/content/108/37/15253.full
If the whole thing is too much for you, here’s a bit of the abstract:
“Here, we describe a diverse avifauna from the latest Maastrichtian of western North America, which provides definitive evidence for the persistence of a range of archaic birds to within 300,000 y of the K–Pg boundary. A total of 17 species are identified, including 7 species of archaic bird, representing Enantiornithes, Ichthyornithes, Hesperornithes, and an Apsaravis-like bird. None of these groups are known to survive into the Paleogene, and their persistence into the latest Maastrichtian therefore provides strong evidence for a mass extinction of archaic birds coinciding with the Chicxulub asteroid impact.”
Does everyone always need to hold your hand for you like this? Apparently, since you fell for such an idiotic on its face farce as the gravity “hypothesis”. Here’s the first paragraph of the Results section, showing yet again no time difference whatsoever in the disappearance from the fossil record of both Enantiornithes A & B:
“A total of 15 distinct coracoid morphotypes are identifiable; full descriptions of each are given in the SI Appendix. One enantiornithine has previously been recognized from the assemblage (27), but three species are identified here (Fig. 1 A–C). The largest (Fig. 1A) most likely represents the giant enantiornithine Avisaurus archibaldi (27). Enantiornithine features (31) include a dorsal fossa, a posteriorly projecting coracoid boss, a dorsally oriented glenoid, and a medial fossa, but the coracoid lacks a supracoracoideus nerve foramen or a medial flange and groove. Enantiornithine A (Fig. 1B) is a smaller taxon, characterized by a deep medial fossa, a thin medial flange, and a subtriangular coracoid neck. The smallest form, Enantiornithine B (Fig. 1C), is differentiated by a bulbous, medially notched scapular condyle, a robust medial flange, and an elliptical coracoid neck. provides strong evidence for a mass extinction of archaic birds coinciding with the Chicxulub asteroid impact.”
If you don’t believe me or the plain evidence of the text, contact the authors of the paper.
2) Can you possibly really be this dense? For the third time, I pointed out that, contrary to your easily shown false assertion that all MEEs have the same causes, ie marine regressions caused by “gravity pulses” & volcanism, the Ordovician event followed the end of volcanism & its sea level regression was caused by glaciation. What possible relevance could the P/Tr (please not correct abbreviation, yet again), about which I said nothing, have to do with this argument? You also continue to evade the inconvenient truth that the Devonian extinctions were accompanied by marine transgression.
3) You clearly have never, ever studied marine biology in general or cephalopod behavior & evolution in particular. Your assertion that nautiloids rise at night to the same level as ammonites inhabited is laughable. Ammonites lived their entire lives above about 100 meters in depth. Nautiloids even when rising at night from 900 to 2000 feet, rarely if ever got as high as 100 meters. Normal for modern Nautilus species is 500 to 300 feet, just 30 feet within the the 100 meter level for fleeting moments if at all. There would have been no reason for them to rise even that high during the K/T event. Most of their food at those shallow depths would have been dead.
4) Apparently you have never looked at a map of Pangaea. In the NH, there was more land at high latitudes while it was conjoined than at the K/T (bear in mind that continental crust can lie under shallow seas). In the SH, about the same amount lay above 60 degrees South, if less above 70 or 80. In any case, the effect would have been tiny, as elementary arithmetic would show any sane person of normal intelligence. The oceanic & continental crust is a minute fraction of the diameter & mass of the earth. The slight differences in its distribution are less than trivial.
5) I have no vested interest in the K/T extinction. I am interested in the integrity of science. Advances & new paradigms, overturning orthodoxies, have never arisen from the lunatic fringe, but from real, hard-working, brave honest scientists doing valid research or calculation for lifetimes, like Copernicus, Kepler, Galileo, Newton, Lavoisier, Darwin, Wegener & Bretz, whose work is as different from your idle, baseless, prima facie false speculation as is humanly possible.
PS: I would add the Alvarezes to that list of great paradigm-shifters. Had you ever actually read their work or the hugely productive research that has followed in the wake of their hypothesis, now a well-established theory, maybe you could have saved yourself a lot of public embarrassment.
@John Tillman,
The following is a quote from another website which displayed the same chart you posted:
“The effect of the Cretaceous-Paleogene (K-Pg) (formerly Cretaceous–Tertiary, K–T) mass extinction on avian evolution is debated, primarily because of the poor fossil record of Late Cretaceous birds. In particular, it REMAINS UNCLEAR whether archaic birds became extinct gradually over the course of the Cretaceous or whether they remained diverse up to the end of the Cretaceous and perished in the K–Pg mass extinction.”
The emphasis of “remains unclear” is mine and 300,000 years is a long time.
If you don’t think nautiloids come to the surface of the water at night then read Peter Ward’s books.
You wrote in an earlier post:
“The impact affects would thuns have hit them harder than nautiloids because ammonite larva were planktonic, high in the water column. Nautiloid eggs are large & stay deeper.”
Now you write:
“Ammonites lived their entire lives above about 100 meters in depth.”
YOU KEEP CONTRADICTING YOURSELF!
You wrote:
“I pointed out that, contrary to your easily shown false assertion that all MEEs have the same causes, ie marine regressions caused by “gravity pulses” & volcanism…..”
Your density is showing again. Let me explain it, hopefully one last time.
The core elements (all 3 of them) are able to move off-center when a large continental mass (especially a supercontinent) moves latitudinally so that its center of mass moves away from the equator. When that happens surface gravity lowers. When the reverse happens, surface gravity increases causing extinctions. Coeval with the gravity increase sea level drops which can release methane from the sea bottom, causing another wave of extinction, bot on land and in the sea. Flood basalt volcanism results from the core elements moving back toward Earth-centricity, which is initiated at the core mantle boundary and takes an extended period of time before it reaches the surface.
If you don’t understand why the continental plate movement shifts the core elements then pick up an elementary physics book and read about the conservation of angular momentum.
The regression is followed by a transgression, which you have noted concerning the Devonian but is common to all mass extinctions.
I can make no sense of your ramblings about the land distribution of Pangea, north and south. If you read the pdf link I provided you should know, based on the charts provided by the French research group, that Pangea moved well south of the equator prior to 250mya and well north of the equator after 250mya. Do I have to hold your hand?
If you know anything about those scientists you listed, you would know they were all considered crackpots until their theories were accepted.
@John Tillman,
You might want to read Peter Ward’s book ‘ In Search of Nautilus’ in which you will find the following quote:
“Soon after nightfall large specimens of Nautilus macromphalus can be seen in the shallow areas of the outer barrier reef.”
The Alvarez’s theory about extinction will eventually be discarded. It’s only a matter of time.
I have read it. Apparently you have not. Nor did you read what I said.
Nautiluses seldom get as high as the 100 meter level, which was about the floor for ammonites, as I tried to educate you.
Ward considers “shallow” to be 160 to 225 meters:
PLoS One. 2011 Feb 22;6(2):e16311. doi: 10.1371/journal.pone.0016311.
Vertical distribution and migration patterns of Nautilus pompilius.
Dunstan AJ, Ward PD, Marshall NJ.
Source
School of Biomedical Science, University of Queensland, Brisbane, Queensland, Australia. andy.dunstan@gmail.com
Abstract
Vertical depth migrations into shallower waters at night by the chambered cephalopod Nautilus were first hypothesized early in the early 20(th) Century. Subsequent studies have supported the hypothesis that Nautilus spend daytime hours at depth and only ascend to around 200 m at night. Here we challenge this idea of a universal Nautilus behavior. Ultrasonic telemetry techniques were employed to track eleven specimens of Nautilus pompilius for variable times ranging from one to 78 days at Osprey Reef, Coral Sea, Australia. To supplement these observations, six remotely operated vehicle (ROV) dives were conducted at the same location to provide 29 hours of observations from 100 to 800 meter depths which sighted an additional 48 individuals, including five juveniles, all deeper than 489 m. The resulting data suggest virtually continuous, nightly movement between depths of 130 to 700 m, with daytime behavior split between either virtual stasis in the relatively shallow 160-225 m depths or active foraging in depths between 489 to 700 m. The findings also extend the known habitable depth range of Nautilus to 700 m, demonstrate juvenile distribution within the same habitat as adults and document daytime feeding behavior. These data support a hypothesis that, contrary to previously observed diurnal patterns of shallower at night than day, more complex vertical movement patterns may exist in at least this, and perhaps all other Nautilus populations. These are most likely dictated by optimal feeding substrate, avoidance of daytime visual predators, requirements for resting periods at 200 m to regain neutral buoyancy, upper temperature limits of around 25°C and implosion depths of 800 m. The slope, terrain and biological community of the various geographically separated Nautilus populations may provide different permutations and combinations of the above factors resulting in preferred vertical movement strategies most suited for each population.
Here’s a graph of their recorded movements, since actually reading & absorbing text appears to be beyond your ability:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043052/figure/pone-0016311-g003/
Ward, like everyone else, uses ROVs & cameras to study them. You can’t sit in a boat on the surface & see them at night. They’re mostly below 150 meters, precisely as I told you. Had you bothered to do any actual research in looking to support your lunatic fantasy, you’d already have learned this.
BTW, deep-diving nautiluses are so hard to study that people have died doing so.
Please state what findings you think could possibly falsify the Alvarez’ impact theory, which has withstood attack from every possible angle for over 30 years? Walter states that the impact was preceded by other stresses on life preceding it, such as land volcanism (Deccan Traps) & marine regression (due to lowered undersea volcanism, a slightly cooler climate & possibly other causes). But study after study has found that the mass extinctions occurred almost simultaneously (within ability to measure) with the now well-date impact. The bird study you refuse to read is one.
@John Tillman,
Let me add the text that was in Ward’s book:
“….have observed what native fisherman have long known: soon after nightfall large specimens of Nautilus macromphalus can be seen in the shallow areas of the outer barrier reef.”
I’ll rely on Ward’s expertise rather than a study you offer. I didn’t see the number of tagged specimens used in the study nor whether it was conducted near a reef, which would offer protection to the nautilus to ascend higher.
Also, describing what the nautilus fed on, the spiny lobster genus Panulirus, he stated that they live on the top 30 to 40 feet of the outer reef (in New Caledonia).
Even your reference states:
“The slope, terrain and biological community of the various geographically separated Nautilus populations may provide different permutations and combinations of the above factors resulting in preferred vertical movement strategies most suited for each population.”
The Alvarez theory, after 30 years is still not accepted. Yes, the impact did occur at that time but two other theories are debated, volcanism and my theory.
If the Alvarez theory were valid there would be a lot of “bone piles” near the clay layer. Where are they? I’m not aware of any, are you?
The reality is that dinosaurs were disappearing gradually over the late Cretaceous and fossils in the 3 meter depth below the clay layer are minuscule.
The theory I support (increasing surface gravity) is the only one that can explain the observed effects. Even the extinction of all marsupials in N. America supports this theory.
“But study after study has found that the mass extinctions occurred almost simultaneously (within ability to measure) with the now well-date impact. The bird study you refuse to read is one.”
The assumption that all the extinctions took place at the time of the impact instead of some other time within the 300,000 year has no basis.
“Cum hoc ergo propter hoc”
Are you blind?
The study I showed you was by Ward & a colleague. Do you read?
When Ward says “shallow”, he means relative to the depths at which nautiluses spend most of their time. Again I ask, can you really be this dumb?
Clearly paleontology & geology are also sciences you’ve never studied. There would not be bone piles at the boundary because very few living things ever fossilize, which should be obvious. Collections within 300,000 years are at the resolution ability, as you’ve been shown over & over by actual paleontologists. That’s the blink of an eye in geological time.
The Alvarez’ theory isn’t an example of cum hoc. It’s an explanation for the extinctions that had already been observed, long before. Science has now been able to fix the dates of both the impact & the extinctions more closely, & yes, they do correlate as precisely as can be measured. But the clincher for the theory is that it explains the pattern of extinctions, which your fantasy fails miserably to do.
The extent to which non-avian dinosaurs were in decline is highly controversial. Your assertion overlooks mountains of evidence. To the extent that there is a consensus now, it favors dino diversity right up to the impact (see Wang, 2006, & ), Barrett’s 2009 study notwithstanding. Older work supporting lower late Maastrichtian diversity suffered from poor sampling & taphonomic problems.
But of course actually researching this topic would require too much work for you.
http://bsgf.geoscienceworld.org/content/183/6/547.abstract
But even if non-avian dinos were in decline (as pterosaurs certainly were, probably due to birds), that would not obviate the robust conclusion that the impact wiped them out long before they would have gone extinct at a background rate. Indeed, they might still be with us to some extent, as are birds. The smallest dino known lives right now in Cuba. Of course a tinier bird would be unlikely to be found as a fossil.
@John Tillman,
Your immature comments show that you are the one that is dumb and getting desperate. If it is too hot in the kitchen……………..
The missing “bone piles” at the K-T transition cannot be attributed to the Signor Lipps effect. Your entire support of the impact’s responsibility for the extinctions is unsupportable. If 75% of species were killed by the asteroid, which would have happened within days, months and less likely, years, there would be many “bone piles.”
As I’ve tried to explain to you, pterosaurs were gradually getting larger (wing area/body mass ratio) during the late Cretaceous to compensate for a gradual increase in surface gravity. The rapid high pulse of increasing surface gravity at the K-T transition would have had to be coeval with the massive marine regression if the Gravity Theory of Mass Extinction is valid. This is the reason the pterosaurs as well as all other terrestrial fauna that disappeared became extinct. It had nothing to do with competition from birds, which were minuscule compared to pterosaurs.
The 300,000 year window of extinction is your crutch!
Cum hoc ergo propter hoc!
There is no reason to imagine we would have discovered any bone piles. There may be some fossilized piles in the crust of the earth at the K/T boundary, but the odds of finding them in the few outcrops of the right age are vanishingly small. The resolution of 300,000 years is a taphonomic fact, not a crutch.
The mass extinction is visible in the fossil record because many species below the line don’t exist above the K/T boundary. That their near-simultaneous disappearance was rapid is evident in the record as well.
Pterosaurs did not slowly get larger during the Maastrichtian. They were already large. An azhdarchid vertebra was reported in 2010 from the EK (~140 Ma) & genus Lacusovagus is known from ~120 Ma. But this family of giant pterosaurs is primarily found in the LK (108 Ma) & was the only one known still extant at the K/T, although many genera in it had already gone extinct by then. There were also other giant (wingspan 16-36′) families which died out in the EK & LK long before the K/T, like the genera Ornithocheirus, Coloborhynchus, Cearadactylus, Caulkicephalus Liaoningopterus (same family as preceding four), Pteranodon, Geosternbergia (same family as Pteranodon), Moganopterus, Santanadactylus & Istiodactylus. So yet again your total ignorance is on humiliating display.
What is noticeable during the LK is the progressive extinction of small pterosaurs, due to competition from birds. Only the few largest arzhdachid species survived to be wiped out by the impact. They are a fascinating family. You should study them before commenting on their evolution, the nature of which falsifies your baseless assertion.
The so-called “Gravity Theory” isn’t a theory, isn’t valid & in fact is completely without a single shred of supporting evidence.
Your willful ignorance & lame excuse making are aggravating. It’s the wrestling with a lunatic pig syndrome, which I’ve been crazy not to avoid.
@John Tillman,
Based on your immature comments I have to assume you are still in high school.
Your support of the asteroid impact hypothesis is based on conjecture only, because you cannot and have not provided any references to dinosaur fossils that can be linked to the proximity of the clay layer. You can make all the excuses that you like but you will never find those references. There were few, if any, dinosaurs alive at the time of the impact.
Yes, I misspoke when I stated that the pterosaurs were getting larger in the late Cretaceous. I should have omitted the adjective “late.” Pterosaurs were getting larger throughout the entire Cretaceous because they were evolving in an environment where surface gravity was increasing. If you have another explanation for the size increase, please provide it.
The Gravity Theory of Mass Extinction can explain ALL mass extinctions, the common cause of which is an increase in surface gravity. I will repeat my prior post:
The core elements (all 3 of them) are able to move off-center when a large continental mass (especially a supercontinent) moves latitudinally so that its center of mass moves away from the equator. When that happens surface gravity lowers. When the reverse happens, surface gravity increases causing extinctions. Coeval with the gravity increase, sea level drops which can release methane from the sea bottom, causing another wave of extinction, both on land and in the sea. Flood basalt volcanism results from the core elements moving back toward Earth-centricity, which is initiated at the core mantle boundary and takes an extended period of time before it reaches the surface.
View Figure 11 in the following study of the Triassic-Jurassic extinction. The chart, if you examine it carefully, is precisely what the GTME would predict for all mass extinctions. However, as noted in a prior comment, the release of methane in pre-Permian extinctions would be absent because it was the Carboniferous period where massive amount of carbon were buried at the sea bottom forming the methane hydrates.
http://onlinelibrary.wiley.com/doi/10.1111/pala.12034/full