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Natural Science Forum / Biology / Paleontology / May 2007Could Be the Reason
While I agree that it is possible that an asteroid impact caused the extinction of the dinosaurs, there are other possibilities. The sun's output is not necessarily constant. There are many variable stars and a fluctuation of as little as 1% in solar output could have dramatic consequences. What was responsible for the ice ages? Also, depletion of atmospheric carbon dioxide by plants and organisms could cause a reduction of average temperatures. There is quite a lot of carbon locked-up in coal and petroleum and in carbonate rock. Richard Nacamuli Richard L. Nacamuli > While I agree that it is possible that an asteroid impact caused the > extinction of the dinosaurs, > there are other possibilities. Do any of these other possibilities result in a worldwide layer of iridium-enriched mud, shocked quartz, and tektites? > The sun's output is not necessarily > constant. There are many variable > stars and a fluctuation of as little as 1% in solar output could have > dramatic consequences. > What was responsible for the ice ages? Milankovitch cycles. > Also, depletion of atmospheric > carbon dioxide by plants > and organisms could cause a reduction of average temperatures. There > is quite a lot of carbon > locked-up in coal and petroleum and in carbonate rock. Any evidence for a sharp climate change at the K/T boundary? >> The sun's output is not necessarily >> constant. There are many variable [quoted text clipped - 3 lines] > > Milankovitch cycles. But Milankovitch doesn't explain lack of ice ages in the Devonian, Triassic, Jurassic ... and more. >>>The sun's output is not necessarily >>>constant. There are many variable [quoted text clipped - 6 lines] > But Milankovitch doesn't explain lack of ice ages in the Devonian, > Triassic, Jurassic ... and more. I'm sure that oceanic currents influenced by continental distributions have a lot to say about it. The real question is whether this has anything to do with the K/T extinction. >>> The sun's output is not necessarily >>> constant. There are many variable [quoted text clipped - 6 lines] > But Milankovitch doesn't explain lack of ice ages in the Devonian, > Triassic, Jurassic ... and more. It is claimed that the position of the continents combined with the uplift that produce the Himalayas triggered the cycle of ice ages. >> While I agree that it is possible that an asteroid impact caused the >> extinction of the dinosaurs, [quoted text clipped - 18 lines] > > Any evidence for a sharp climate change at the K/T boundary? Major geologic changes were occuring but the climate didn't do a significant cool off until much later to the best of my knowledge. >>>While I agree that it is possible that an asteroid impact caused the >>>extinction of the dinosaurs, [quoted text clipped - 21 lines] > Major geologic changes were occuring but the climate didn't do a significant > cool off until much later to the best of my knowledge. Egzackly. >> While I agree that it is possible that an asteroid impact caused the >> extinction of the dinosaurs, >> there are other possibilities. > > Do any of these other possibilities result in a worldwide layer of > iridium-enriched mud, shocked quartz, and tektites? Please explain the even larger impacts that did NOT result in mass extinctions. >>> While I agree that it is possible that an asteroid impact caused the >>> extinction of the dinosaurs, [quoted text clipped - 5 lines] > Please explain the even larger impacts that did NOT result in mass > extinctions. A lot of things were going on that could have stressed some organisms. The impact would have made conditions much worse. Which larger impacts did not cause mass extinctions? >> While I agree that it is possible that an asteroid impact caused the >> extinction of the dinosaurs, >> there are other possibilities. > > Do any of these other possibilities result in a worldwide layer of > iridium-enriched mud, shocked quartz, and tektites? There was certainly a major impact at K-T boundary, but was that the only cause of the mass extinction ? A major flood basalt eruption was going on at the same time (Deccan Traps). Several other mass extinctions, such as end-Permian (Siberian Traps) and end-Triassic (Central Atlantic) mass extinctions also happened at the same time as major flood basalt eruptions. Could there not be a cause-effect link between such eruptions and mass extinction ? On the otherhand evidence for an impact is non-existent, in spite of quite extensive search, for mass extinctions other than at the K-T boundary.  Signaturegautam >>> While I agree that it is possible that an asteroid impact caused the >>> extinction of the dinosaurs, [quoted text clipped - 12 lines] > non-existent, in spite of quite extensive search, for mass extinctions > other than at the K-T boundary. I don't know much about it but there was a localized one in South America. I listened watched a broadcast that seems to link major impacts with major basalt flooding events but I leave it to others to fight that war. |
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