Talk:Cretaceous–Tertiary extinction event

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[edit] Multiple impact event paragraph

This paragraph currently only relies on sources from Leslie Mullen that are all from website http://www.astrobio.net. This is a NASA-sponsored online popular science magazine, so it sounds to me a scientific reviewed source would be required. Actually in view of the latest Science article, I wonder if we should not just delete the paragraph. --Anneyh (talk) 11:32, 7 March 2010 (UTC)

I think: 1. we can rely on NASA-sponsored online popular science magazines, 2. "committee science" is a grave mistake, scientific debates shall not be shushed by committee decisions, so alternate view should be kept, even though they can be downplayed if the support diminishes. Rursus dixit. (mbork3!) 06:14, 8 March 2010 (UTC)
Sorry, but we have another 'All reputable scientists agree'. So saying "The climate was prone to violent natural changes even before man came along with his CO2...look what happened to the Dinosaurs", is now heresy. Well done, your research grants will be renewed :-) 81.157.16.194 (talk) 18:39, 8 March 2010 (UTC)
Er, I don't think it would be heresy to say that there were extreme environmental excursions before humans (eg the glacial/interglacial cycles [E Vrba, Palaeoclimate and evolution], Dansgaard-Oeschger cycles, or the Palaeocene-Eocene thermal maximum, which is currently interpreted as a natural greenhouse-gas induced environmental catastrophe). But it would be considered odd to suggest that because the climate has undergone violent excursions naturally, the climate system is therefore safe from human interventions. Orbitalforam (talk) 15:06, 1 May 2010 (UTC)
Gerta Keller and Vincent Courtillot do not agree with Chicxulub as a single cause, they believe rather in multiple causes: global marine regression, Chicxulub hit, Shiva hit, Deccan flood basalts. Many extinction events are related to marine regressions and flood basalts. Researchers (leaded by David J. Archiblad) in the fields of terrestrial vertebrates, including dinossaurs, as well as freshwater vertebrates and invertebrates seem to not like the single cause idea as well. Shiva left an Ir deposit and had a diameter of 40 km, Chicxulub did not leave an Ir deposit and had a diameter of 10 km. If this group tells the truth, the single cause hypothesis does not have a chance. Schulte et al. is only a review of old literature, nothing new. --Chris.urs-o (talk) 14:27, 11 August 2010 (UTC)
In the article there is a paragraph about multiple impact events (that is different from multiple causes), referring for example to the Boltysh crater. The paragraph is only sourced by a serie of articles from Leslie Mullen in astrobio.net, one of these being [1]. I saw you made extensive bibliography search and I wonder how often this hypothesis is proposed in publications. --Anneyh (talk) 15:01, 11 August 2010 (UTC)
It is not a search. They are mostly the 30 refs. of the 3 letters answering Schulte et al. (2010) Science article. I just wanted to help with an up to date overview of the literature. The summaries of the refs. do not discuss this multiple impact hypothesis. Shiva was deadly because it hit the potential seafloor spreading ridge, causing probably most of the Deccan traps. Triggering flood basalts was important, the impacts were not as bad. My personal feeling after some reading. --Chris.urs-o (talk) 16:24, 11 August 2010 (UTC)
Anneyh, I do not really know. If the multiple impacts come from a break up, they must have similar latitudes and hit times. If Shiva got a diameter of 40 km, the other asteroids must have similar diameters to be relevant. If Chicxulub is smaller, it can't be the main cause. The other asteroids to be K/T relevant must hit the Earth at similar times. Maybe (Courtillot, V. (1994). "Mass extinctions in the last 300 million years: One impact and seven flood basalts?". Israel Journal of Earth Sciences 43: 255–266. ) is a seminal paper, and K/T is a flood basalt event too, triggered by an impact. The Shiva impact probably activated the ridge between Seychelles and the Indian Plate, inactivating the ridge between Madagascar and Seychelles (Chatterjee, Sankar (15 October 2009). "Giant Impact Near India -- Not Mexico -- May Have Doomed Dinosaurs". 2009 Annual GSA Meeting, 18-21 October. The Geological Society of America Release No. 09-54. http://www.geosociety.org/news/pr/09-54.htm. Retrieved 13 August 2010. ). I'll add 2 refs, so the section gets a total of 2 refs. and Leslie Mullen ;) --Chris.urs-o (talk) 08:11, 13 August 2010 (UTC)
But Gerta Keller disagrees (Moskowitz, Clara (18 October 2009). "New Dino-destroying Theory Fuels Hot Debate". space.com. http://www.space.com/scienceastronomy/091018-dinosaur-crater.html. ). --Chris.urs-o (talk) 10:00, 13 August 2010 (UTC)

[edit] March 2010 Science article

I have strengthened the statements about the March 2010 Science article in two regards. First the panel did not just support "an asteroid impact" but specifically the Chicxulub impact and no other as the triggering event. Second, they did not conclude that this was the most likely hypothesis but were unequivocal that it was the cause. Being competent scientists they presumably would accept that all scientific conclusions are provisional, and I very much doubt that they expect proponents of alternative theories to throw in the towel just because of this report (which in fact makes no attempt to interpret the evidence from the point of view of any of the rival theories). Nevertheless they chose to report their results as being as close to a sure thing as one can get in science, and our summary of their work should reflect that. PaddyLeahy (talk) 19:09, 8 March 2010 (UTC)

That's what I mean too. It is a fact that the dinosaurs died out 'about' 65.5 mya, and it is a fact that a large asteroid struck the earth 'about' 65.5 mya. But...'about' noon tomorrow means any time from 11:30 to 12:30. How wide is 'about' from a range of 65.5 million years?. How can we possibly know from so long ago that the dinosaurs had not been in terminal decline for hundreds of thousands of years before for other more subtle reasons, and the asteroid bumped-off the last few? 81.157.16.194 (talk) 19:25, 8 March 2010 (UTC)
As of the time that I'm leaving the comment, the wording indicates that the Chicxulub impact triggered the extinction. I think this is a fair wording, as triggered does not present the impact as the lone exterminating event, so much as the key event that kicked off a number of other events which together caused the mass extinction. This allows for the representation of a theory which cannot be proven or disproven with current evidence, while also presenting this theory as that which has the most evidence supporting it. Hiberniantears (talk) 16:01, 9 March 2010 (UTC)
Yes, for example it's always possible that JFK had a heart attack just before the assassin's bullets entered his body. But not probable. We never know for certain, that's true - but there is such a thing as reasonable certainty, with the proviso that new evidence could overturn it. Orbitalforam (talk) 16:29, 16 April 2010 (UTC)
The controversy is not over yet. The Economist, I am become Death, destroyer of worlds: The story of how the dinosaurs disappeared is getting more and more complicated -- From a note by User Legis about Sankar Chatterjee - 2 November 2009. --Chris.urs-o (talk) 08:56, 13 August 2010 (UTC)

[edit] Literature of the Controversy

[edit] Single Cause

[edit] Gerta Keller Group

[edit] Vincent Courtillot

  • Anne-Lise Chenet Frédéric Fluteau Vincent Courtillot Martine Gérard K. V. Subbarao (2008). "Determination of rapid Deccan eruptions across the Cretaceous-Tertiary boundary using paleomagnetic secular variation: Results from a 1200-m-thick section in the Mahabaleshwar escarpment". Journal of Geophysical Research 113 (B04101): 27. doi:10.1029/2006JB004635. 
  • Anne-Lise Chenet, Xavier Quidelleur, Frédéric Fluteau, Vincent Courtillot and Sunil Bajpai (15 November 2007). "40K–40Ar dating of the Main Deccan large igneous province: Further evidence of KTB age and short duration". Earth and Planetary Science Letters 263 (1–2): 1–15. doi:10.1016/j.epsl.2007.07.011. 
  • Anne-Lise Chenet Vincent Courtillot Frédéric Fluteau Martine Gérard Xavier Quidelleur S. F. R. Khadri K. V. Subbarao Thor Thordarson (2009). "Determination of rapid Deccan eruptions across the Cretaceous-Tertiary boundary using paleomagnetic secular variation: 2. Constraints from analysis of eight new sections and synthesis for a 3500-m-thick composite section". Journal of Geophysical Research 114 (B06103): 38. doi:10.1029/2008JB005644. 
  • Vincent Courtillot, Jean Besse, Didier Vandamme, Raymond Montigny, Jean-Jacques Jaeger and Henri Cappetta (November 1986). "Deccan flood basalts at the Cretaceous/Tertiary boundary?". Earth and Planetary Science Letters 80 (3–4): 361–374. doi:10.1016/0012-821X(86)90118-4. 
  • Courtillot, V. (1994). "Mass extinctions in the last 300 million years: One impact and seven flood basalts?". Israel Journal of Earth Sciences 43: 255–266. 
  • Courtillot, Vincent (1999). Evolutionary Catastrophes: the Science of Mass Extinction. Joe McClinton. Cambridge: Cambridge University Press. ISBN 0521583926. 
  • Vincent E. Courtillot and Paul R. Renne (January 2003). "On the ages of flood basalt events". Comptes Rendus Geosciences 335 (1): 113–140. doi:10.1016/S1631-0713(03)00006-3. 
  • V. Courtillot, Y. Gallet, R. Rocchia, G. Féraud, E. Robin, C. Hofmann, N. Bhandari and Z. G. Ghevariya (30 October 2000). "Cosmic markers, 40Ar/39Ar dating and paleomagnetism of the KT sections in the Anjar Area of the Deccan large igneous province". Earth and Planetary Science Letters 182 (2): 137–156. doi:10.1016/S0012-821X(00)00238-7. 

[edit] Others

  • Michael L. Prauss (10 December 2009). "The K/Pg boundary at Brazos-River, Texas, USA — An approach by marine palynology". Palaeogeography, Palaeoclimatology, Palaeoecology 283 (3–4): 195–215. doi:10.1016/j.palaeo.2009.09.024. 
  • Paul M. Barrett, Alistair J. McGowan, and Victoria Page (22 July 2009). "Dinosaur diversity and the rock record". Proc. R. Soc. B 276 (1667): 2667–2674. doi:10.1098/rspb.2009.0352. PMC 2686664. PMID 19403535. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2686664. 
  • Nan Crystal Arens and Ian D. West (November 2008). "Press-pulse: a general theory of mass extinction?". Paleobiology 34 (4): 456–471. doi:10.1666/07034.1. 
  • Shanan E. Peters (31 July 2008). "Environmental determinants of extinction selectivity in the fossil record". Nature 454 (7204): 626–629. doi:10.1038/nature07032. PMID 18552839. 
  • Stephen Self, Mike Widdowson, Thorvaldur Thordarson and Anne. E. Jay (15 August 2006). "Volatile fluxes during flood basalt eruptions and potential effects on the global environment: A Deccan perspective". Earth and Planetary Science Letters 248 (1–2): 518–532. doi:10.1016/j.epsl.2006.05.041. 
  • Gregory P Wilson (2005). "Mammalian faunal dynamics during the last 1.8 million years of the Cretaceous in Garfield County, Montana". Journal of Mammalian Evolution 12 (1–2): 53–76. doi:10.1007/s10914-005-6943-4. 
  • David, Archibald; David Fastovsky (2004). "Dinosaur Extinction". In Weishampel David B, Dodson Peter, Osmólska Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 672–684. ISBN 0-520-24209-2. http://www.bio.sdsu.edu/faculty/archibald/ArchFast.pdf. 
  • MacLeod, N. (2003). "The causes of Phanerozoic extinctions". In LJ Rothschild and AM Lister. Evolution on Planet Earth. Academic Press. pp. 253–277. 
  • C. Wylie Poag, Jeffrey B. Plescia and Phillip C. Molzer (2002). "Ancient impact structures on modern continental shelves: The Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin of North America". Deep Sea Research Part II: Topical Studies in Oceanography 49 (6): 1081–1102. doi:10.1016/S0967-0645(01)00144-8. 
  • P. B. Wignall (March 2001). "Large igneous provinces and mass extinctions". Earth-Science Reviews 53 (1–2): 1–33. doi:10.1016/S0012-8252(00)00037-4. "Comparing the timing of mass extinctions with the formation age of large igneous provinces reveals a close correspondence in five cases, but previous claims that all such provinces coincide with extinction events are unduly optimistic. The best correlation occurs for four consecutive mid-Phanerozoic examples, namely the end-Guadalupian extinction/Emeishan flood basalts, the end-Permian extinction/Siberian Traps, the end-Triassic extinction/central Atlantic volcanism and the early Toarcian extinction/Karoo Traps. Curiously, the onset of eruptions slightly post-dates the main phase of extinctions in these examples. Of the seven post-Karoo provinces, only the Deccan Traps coincide with a mass extinction, but in this case, the nature of the biotic crisis is best reconciled with the effects of a major bolide impact. Intraoceanic volcanism may also be implicated in a relatively minor end-Cenomanian extinction crisis, although once again the main phase of volcanism occurs after the crisis." 
  • N. MacLeod, P. F. Rawson, P. L. Forey, F. T. Banner, M. K. Boudagher-Fadel, P. R. Bown, J. A. Burnett, P. Chambers, S. Culver, S. E. Evans, C. Jeffery, M. A. Kaminski, A. R. Lord, A. C. Milner, A. R. Milner, N. Morris, E. Owen, B. R. Rosen, A. B. Smith, P. D. Taylor, E. Urquhart and J. R. Young (April 1997). "The Cretaceous-Tertiary biotic transition". Journal of the Geological Society 154 (2): 265–292. doi:10.1144/gsjgs.154.2.0265. 
  • Bhandari, N., P. N. Shukla, Z. G. Ghevariya, and S. M. Sundaram (1995). "Impact did not trigger Deccan volcanism: Evidence from Anjar K/T Boundary intertrappean sediments". Geophysical Research Letters 22 (4): 433–436. doi:10.1029/94GL03271. 
  • Rampino MR, Stothers RB (5 Aug 1988). "Flood Basalt Volcanism During the Past 250 Million Years". Science 241 (4866): 663–668. doi:10.1126/science.241.4866.663. PMID 17839077. 

[edit] Sankar Chatterjee

[edit] The Shiva hypothesis

  • The Shiva hypothesis
  • Rampino, Michael R.; Caldeira, Ken (1992). "Episodes of terrestrial geologic activity during the past 260 million years: A quantitative approach Celestial Mechanics and Dynamical Astronomy". Celestial Mechanics and Dynamical Astronomy 54 (1–3): 143–159. doi:10.1007/BF00049549. 
  • Rampino, MR; Haggerty, BM (4 Aug 1995). "Mass extinctions and periodicity". Science 269 (5224): 617–9. doi:10.1126/science.7624783. PMID 7624783. 
  • Rampino, Michael R.; Haggerty, Bruce M. (1996). "The “Shiva Hypothesis”: Impacts, mass extinctions, and the galaxy". Earth, Moon, and Planets 71 (3): 441–460. doi:10.1007/BF00117548. 
  • Rampino, MR; Haggerty BM, Pagano TC (1997 May 30). "A unified theory of impact crises and mass extinctions: quantitative tests". Ann N Y Acad Sci 822: 403–31. doi:10.1111/j.1749-6632.1997.tb48358.x. PMID 11543121. 
  • --Chris.urs-o (talk) 23:00, 10 August 2010 (UTC)
  • These are mostly the references given by the response letters to Schulte et al. Science article. Sankar Chatterjee and the Michael R. Rampino's Shiva hypothesis are given for the sake of completeness. Science and Nature articles are more review type articles than most articles. --Chris.urs-o (talk) 14:17, 11 August 2010 (UTC)/ --Chris.urs-o (talk) 09:15, 13 August 2010 (UTC)

[edit] Cephalopoda

"Except for nautiloids (represented by the modern order Nautilida) and coleoids (which had already diverged into modern octopodes, squids, and cuttlefish) all other species of the molluscan class Cephalopoda became extinct at the K–T boundary. These included the ecologically significant belemnoids, as well as the ammonoids, a group of highly diverse, numerous, and widely distributed shelled cephalopods."

Isn't this sentence a bit too complicated ? Moreover, it's false because belemnites are coleoids. Nautiloids, except for being paraphyletic, were also represented only by Nautilida, which are extant. So, major extinctions at the K-T boundary affected only Ammonoids and Belemnites. It would be more simple to say that, if you agree.N@ldo (talk) 15:13, 18 February 2011 (UTC)

[edit] Edit reverted, please double-check

I made an edit to improve readability of the first few sentences. It was quickly reverted, with the comment that the edit was "huge" and "some of it not clear", disagreeing with my comment that it was "some minor copy-editing".

I then reviewed my edit and found that it changed the following:

  • "large-scale" to "large"
  • "K is the abbreviation for" to "K stands for" (2x)
  • "Non-[[bird|avian]] [[dinosaur]] [[fossils]]" to "[[Fossils]] from non-[[bird]] [[dinosaurs]] (non-avian dinosaurs)"
  • sentence order ("aaa bbb" -> "bbb aaa")
  • punctuation such as splitting "aaa, bbb" -> "aaa. Bbb"
  • inserted a linebreak

I would maintain that these changes are indeed small, not "huge". It may seem bigger because linebreaks get shown as a big red splotch followed by a big green splotch, but that's something well-known which the diff display has done forever. Also, I don't see how the edit in question made things less clear.

Having checked, I can't see what is so problematic about the edit, so I think the reverting was not justified. Please review the edit and re-apply it. Thank you. --84.130.44.73 (talk) 03:31, 13 April 2011 (UTC)

I made the reversion. Non-avian dinosaur fossils is so much clearer. Revert stands unless you've got some compelling reasons that are more convincing than what you state. OrangeMarlin Talk• Contributions 03:53, 13 April 2011 (UTC)
I'm of the opinion that the change did not improve the readability of the article. Some of the changes probably have merit, but "non-bird dinosaurs (non-avian dinosaurs)" is awkward, and "stands for" is both informal and ambiguous. "Is the abbreviation for" really is much better here. I'm not opposed to a reworking of some of the wording in the lede, but some of the changes made don't improve the article. Firsfron of Ronchester 06:18, 13 April 2011 (UTC)
Sometimes it's best to makes edits one at a time so that the "good" doesn't get reverted with the "bad". JIMp talk·cont 02:38, 27 April 2011 (UTC)

[edit] K-Pg

The Cretaceous is a geologic period - the period following it is the Paleogene. To call the extinction that occurs at this boundary the "Cretaceous-Tertiary" (K-T) extinction is like calling it the "Maastrichtian-Cenozoic" extinction, or calling the "Permian-Triassic" extinction the "Permian-Mesozoic" extinction; it's identifying the event as the transition from one unit of geologic time to another unit that's of a totally different scale.

I'm fine with the article keeping the K/T title, because that's what most people call it and if it's changed then people might conceivably think they're looking at the wrong subject, but in the body of the article I think it should be written as K/Pg. To do otherwise would be to promote scientific imprecision and perpetuate the misapprehension that the Cretaceous and the Tertiary are geologic equivalents. As the article states, there is a push in geologic circles to try to move away from use of the word Tertiary, and I think the article would be best served by adopting this philosophy. Troodon311 (talk) 22:54, 25 April 2011 (UTC)

Tertiary is no longer used in geologic nomenclature and most (all?) recent technical sources use K-Pg. It hasn't really filtered into popular secondary sources yet, but it would make sense to switch. MMartyniuk (talk) 00:54, 26 April 2011 (UTC)
Not true in North America, at least; K-T is still technical here. There is major no push that I know of (as a geologist) to get rid of the use of "Tertiary". Awickert (talk) 02:24, 27 April 2011 (UTC)

[edit] Ago

It has been suggested that "Ma, assumes BP". The "M" is for "mega" i.e. "million". The "a" is for "annum" i.e. "year". "Ma" means "million years". Where is the implication of "ago"? Sure readers can guess that we mean "65 million years ago" but "65 Ma" doesn't mean "65 million years ago", it means "65 million years". If I wrote "Many species went extinct 65 million years.", I'm sure you'd be able to guess what I mean but you'd want to finish my sentence off. It has been suggested that adding this clarification would confuse the reader. I'd like to suggest that removing it might be even more confusing. JIMp talk·cont 02:14, 27 April 2011 (UTC)

"Ma" in terms of "ago" is standard geological usage. It's come up across many articles on Wikipedia that this is confusing to those who aren't used to it. Suggestions are (1) defining its first occurrence, (2) changing things to "Myr BP" or "Myr ago", or (3) writing out "million years ago". "Ma ago" looks really weird to geologists. Awickert (talk) 02:22, 27 April 2011 (UTC)
Fair enough. I'm no geologist. Things aren't always logicical, even in science ... but if you're using "Ma" for a specific past time, what do you use for a duration (or a future time)? JIMp talk·cont 02:34, 27 April 2011 (UTC)
I use "Myr" for duration personally, though I'm honestly not sure if geologists are consistent about this. I also use Myr as future. I think it's that the "ago" got appended so "ka/Ma/Ga" could be a convenient shorthand, so I use "Xyr" for anything else... but I honestly haven't looked into this too much. Awickert (talk) 03:26, 27 April 2011 (UTC)
It seems that geologists are not yet unanimous on adopting the usage of Ma, but until recently the AGU editorial guidelines used Ma to denote millions of years Before Present (before the epoch January 1, 1950), while using Myr for elapsed times between two events. [2], [3], [4], [5] pertain.LeadSongDog come howl! 03:42, 27 April 2011 (UTC)
All one has to do is click on the Ma wikilink in the article. It clearly states everything. Million years ago is also stated first. Ma ago and Ma BP does look really stupid. It's been Ma for 3 years, gone through an FA and an FAR, been on the main page, and never once has this been brought up. Just because one editor is confused does not mean all are. Can we discuss something relevant or useful? OrangeMarlin Talk• Contributions 04:47, 27 April 2011 (UTC)
Here's what it says when you click on the wikilink: Ma (for megaannum), is a unit of time equal to one million (106) years. It is commonly used in scientific disciplines such as geology, paleontology, and celestial mechanics to signify very long time periods into the past or future. For example, the dinosaur species Tyrannosaurus rex was abundant approximately 65 Ma (65 million years) ago (ago may not always be mentioned; if the quantity is specified while not explicitly discussing a duration, one can assume that "ago" is implied; the alternative but deprecated "mya" unit includes "ago" explicitly.). In astronomical applications, the year used is the Julian year of precisely 365.25 days. In geology and paleontology, the year is not so precise and varies depending on the author.OrangeMarlin Talk• Contributions 04:50, 27 April 2011 (UTC)
One reason why geologists and Palaeontologists have to be a bit more relaxed about the term is that the number of days in the Earth's orbit around the sun has changed somewhat over geological time. cf for example: S J Mazzullo: Length of the year during the Silurian and Devonian periods: new values. Geological Society of America Bulletin 1971, 82, no 4 1085-1086 and Wells, J. W. Coral growth and geochronometry, Nature 1963 187, 948–950 . So the use of an absolute duration for the year (which is not an SI unit) in terms of days could lead to differences between elapsed time and number of orbits, which would be unhelpful. re the K/T acronym: it may be technically inappropriate, but it is widely used, so we may as well accept it for now. Orbitalforam (talk) 09:06, 26 September 2011 (UTC)

[edit] Objection:

The first paragraphs imply that the Dinosaur went extinct at the KT event. This from: "Non-avian dinosaur fossils are found only below the K–T boundary, indicating that non-avian dinosaurs became extinct during the boundary event.[3] A very small number of dinosaur fossils have been found above the K–T boundary, but they have been explained as reworked fossils, that is, fossils that have been eroded from their original locations then preserved in later sedimentary layers.[4][5][6]." This appears to be a paradigm issue. In the later section Evidence the North American Fossils indicate a different pardigm of decline across the Maastrichtian Stage. Any positive extinction evidence is significant and should trump geriatric Chicxulub impact dinosaur extinction rhetoric. This particulary in light of warm blooded Dinosaur prognosis albeit Nova Arctic Dinosaur documentary.
Morbas (talk) 12:38, 30 October 2011 (UTC)

The nature of your objection is unclear. Are you against (non-avian) dinosaurs going extinct at the K-T, because they may have declined beforehand? These two statements are not necessarily exclusive. If you've got a problem with the literature, you should be aware that Wikipedia is not the place for introducing your own theories. J. Spencer (talk) 00:10, 31 October 2011 (UTC)

Jim, you clearly represented the paradigm. I quote the article: "non avian dinosaurs became extinct during the boundary event" but this is not supported by any fossil record. The only evidence is a decline going into and across the lower-mid Maastrichtian Stage. The upper Maastrichtian is void of dinosaur fossil witnessed by the fact that KT is the most researched extinction of the Phanerozoic. No fossils at the KT event threshold, no evidence of non-avian dinosaurs going into the KT event.
The existence of the Arctic Dinosaur coupled with a warm blooded bone growth structure, is the prognosis of the NOVA Arctic Dinosaur supported by a leaf structure indicating a deep seasonal climate above the artic circle. The dinosaur were not dependent on warm climate. The Wiki article presents an unsupported view and this is not the place for introducing your own theories. Morbas (talk) 20:36, 31 October 2011 (UTC)(UTC)
.

There seems to be more than one issue going on here, but dinosaurs were certainly not absent from the late Maastrichtian. Well-established genera more or less limited to the late Maastrichtian include Tyrannosaurus, Ankylosaurus, Pachycephalosaurus, Triceratops, Thescelosaurus, and Edmontosaurus annectens. Are you perhaps thinking of the "3 meter gap" at the top of the Hell Creek Formation? Dinosaur bones are historically absent from the 3 meter gap, but there is evidence that additional study will close this gap, and at any rate the Hell Creek Formation is significantly thicker than 3 m. There's a good, relatively recent summary on the Hell Creek Formation here. (Incidentally, my name is not Jim, but one name's as good as another). J. Spencer (talk) 22:23, 31 October 2011 (UTC)

Honorable J.Spencer then it is...
The 2011 abstract there is evidence indicates the 3m gap is not closed (yet), so we can or cannot use that inference?.
Tyrannosaurus, Ankylosaurus, Pachycephalosaurus, Triceratops, Thescelosaurus, and Edmontosaurus annectens were present late Maastrichtian? Should be some record of that (can you help)? I do not see any dinosaur Stratigraphic position in the Hell Creek Formation article, and once for middle Bakker et al. (2006). Is it not premature to make the statement "non avian dinosaurs became extinct during the boundary event" ? Morbas (talk) 02:37, 1 November 2011 (UTC)

Regarding the 3 m gap: I'd say the reader is free to accept the gap, on the grounds that one fossil is not enough, or to consider the gap closed/in the process of being closed. Alternately, the reader may find the 3 m gap to be, overall, a "red herring;" the Hell Creek Formation is several tens of meters thick altogether, so fossils missing from 3 meters may not be significant.
On the issue of dinosaur fossil distribution in the Hell Creek Formation: I've linked here to a detailed study of the Hell Creek Formation and overlying Fort Union Formation of southwestern North Dakota. The citation is:
Pearson, Dean A.; Schaefer, Terry; Johnson, Kirk R.; Nichols, Douglas J.; and Hunter, John P. (2002). "Vertebrate biostratigraphy of the Hell Creek Formation in southwestern North Dakota and northwestern South Dakota". In Hartman, Joseph H.; Johnson, Kirk R.; and Nichols, Douglas J. (eds.). The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the Northern Great Plains: An Integrated Continental Record of the End of the Cretaceous. Geological Society of America Special Paper, 361. Boulder, Colorado: Geological Society of America. pp. 145–167. ISBN 0-8137-2361-2.
All of the figures were available in this online version, which is very useful. The Google Books link is subject to linkrot, but searching for the title of the article should find it quickly.
A small bit of background: the Hell Creek Formation of southwestern North Dakota ends just before the K-T. This is because its age varies slightly from location to location: the Hell Creek Formation represents a depositional environment that appears at slightly different times over a wide area. In this area, the K-T is found low in the Fort Union Formation, which is the next formation up.
Table 4 (p. 154) of this article is a compilation of all vertebrate species and genera in the Hell Creek Formation of this part of North Dakota and neighboring South Dakota. The assemblage includes rays, sharks, bony fish, frogs, salamanders, turtles, the aquatic reptile Champsosaurus, crocodilians, pterosaurs, theropods, birds, horned dinosaurs, hypsilophodonts, duckbilled dinosaurs, and early mammals. The authors found (Figure 4, p. 155) practically no vertebrate fossils within about the upper two meters of the Hell Creek Formation and lowest meter of the Fort Union Formation. This is not the only fossil gap in the two formations; for example, there is about 20 m without fossils between 60 and 40 m. Figure 5 on p. 157 shows the uppermost slice of these results, calibrated to the K-T boundary. This figure also shows a gap at the top, greater than two meters. Only one fossil was found in this gap: a specimen of a horned dinosaur, at 1.8 m below the boundary.
My reading of these charts is that there are a number of fossils, including dinosaur fossils, almost to the boundary; but the absence of practically any kinds of vertebrate fossils at the very top, and the presence of other sizable fossil gaps lower in the Hell Creek Formation, make it difficult to draw any conclusions about what was specifically happening to dinosaurs during that final gap. The dinosaurs are certainly present very close to the end of the Late Maastrichtian, and they don't show up again in the Paleocene part of the Fort Union beds. J. Spencer (talk) 01:23, 2 November 2011 (UTC)

This discussion is rather pointless. This is Wikipedia: cite or it didn't happen. Your argument that the absence of dino fossils at the exact KT boundary indicated that they may have been extinct before then is your own interpretation of published data, otherwise known as original research. If there is a source that explicitly proposes the same hypothesis it can be included if it's made clear that this is an extreme minority viewpoint. MMartyniuk (talk) 12:46, 2 November 2011 (UTC) The statement "non avian dinosaurs became extinct during the boundary event" is a citation objection. No dinosaur fossil have ever been located at the event layer...to my knowledge. Thus the statement is factually wrong. You may close this section at your leasure
Morbas (talk) 08:43, 7 November 2011 (UTC)

[edit] Time for a name change

"Tertiary" is no longer a formal period in the geologic time scale. The formal name is now "Cretaceous-Paleogene extinction event" and although that is clearly referred to in the article I think the title should reflect this. The name "Cretaceous-Tertiary will still be referred to in the intro so as not to confuse people who aren't familiar with the name change. I attempted to change the title using the DISPLAYTITLE word but it didn't work so I'm not sure if anyone could do this for me. Cadiomals (talk) 00:35, 8 November 2011 (UTC)

Well, then we need to do a name change to the article. It makes no sense now. OrangeMarlin Talk• Contributions 22:23, 29 November 2011 (UTC)
I would appreciate it if someone who actually knows how to change the title would do this for us Cadiomals (talk) 22:58, 1 December 2011 (UTC)
I know that Tertiary is no longer a formal name but KT is pretty commonly used and widely understood. I'd need to see some evidence before supporting a move. I shall consult my personal geologist, who favours preciseness over folk understanding though. Anyone who can be prompted to explode upon the simple reference to pterosaurs as "dinosaurs" can be relied upon to provide a good opinion. Sabine's Sunbird talk 20:42, 27 January 2012 (UTC)
My expert says that although KP may be more technically correct, geologists tend to favour the old usage. Sabine's Sunbird talk 00:18, 29 January 2012 (UTC)
You know how the saying goes: "Old habits die hard." I also have a habit of saying KT just because its easier to say, even though I'm well aware the official name is K-Pg Cadiomals (talk) 00:27, 29 January 2012 (UTC)
Not just an old habit, I've been told it was an unpopular decision that hasn't won universal acceptance amongst geologists. Let alone achieved any recognition outside of geology, literally the first I heard of it was a few days ago on the talk page of bird, and I don't like to think I'm not paying attention. That said, if it what geologists insist upon I guess it is what the article should be called. Sabine's Sunbird talk 03:40, 30 January 2012 (UTC)
Remember that they didn't just change the name of the Tertiary period, they split it in two. I read that this was done for two reasons: 1) to keep it more aligned with the other eras which have more than two periods and 2) The Cenozoic era was one of rapid diversification by mammals so it was necessary to split it into three periods because of the more rapid evolutionary events. Cadiomals (talk) 05:36, 30 January 2012 (UTC)
Retrieved from "http://en.wikipedia.org/w/index.php?title=Talk:Cretaceous%E2%80%93Tertiary_extinction_event&oldid=479762783"
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