Talk:Controversies in Science/What killed the dinosaurs/A critique of More evidence that the Chicxulub impact predates the K/T mass extinction. Meteoritics & Planetary Science
Interesting point by Gerta Keller, yet it is evident that she chooses to ignore certain critical elements. Namely, if she acknowledged a meteor did in fact impact the earth and left a massive crater, what impacts would that have on life in the surrounding region? It is extremely likely that such an event would literally obliterate any land-based dinosaurs. Evidence of remaining animals or organisms after the impact may be true, but not enough is known of the survival capabilities of many organisms or species in the cretaceous period. In addition, how many samples did her study sample in order to arrive at a very specific 300 thousand year discrepancy? (a 0.002% difference). Dlodh574 (talk) 00:52, 9 April 2012 (UTC)
- Yes, there was life after the asteroid hit in the Yucatan Peninsula in northestern Mexico. However, because the asteroid produced large amounts of NOGH-related CH4, it slowly killed off the dinosaurs.--Nzurg (talk) 00:07, 11 April 2012 (UTC)
- I agree with Nzurg, a common misconception of the asteroid theory is that the impact of the asteroid hitting the Earth caused instantanious extinction, when in actuality, studies have shown that the extinction was a lengthy process starting with phytoplankton, moving onto herbivores and eventually, when all other food sources were depleated or gone entirely, the carnivores also starved to death until extinction. Jstal531 (talk) 01:26, 11 April 2012 (UTC)
Just because other life forms survived the meteorite does not mean that the dinosaurs did. Perhaps the life forms that surivived were able to survive in environments that did not require the sun to live, such as the bottom of the ocean. Dinosaurs did require the sun to live, and when the dust particles blocked the sun after the meteorite hit, they died. Bmina836 (talk) 00:02, 13 April 2012 (UTC)
I agree with Bmina836. Every specie requires different envrionments to survive and some can adapt to change quicker and better than others. The dinosaurs could not adapt to the major changes in their environment and slowly died off after the impact. Just because some species were able to survive and there was life afterwards does not make any conslusion about the survival of dinosaurs.Jmay3355 (talk) 22:25, 13 April 2012 (UTC)
- The trajectory model suggests that the photochemical reactions formed ground-level O3 whose concentration was low (1.0 ppm) but much greater than the current level of 0.04 ppm. Because of this, creatures such as amphibians and reptiles survived because they were able to retreat to areas where O3 wouldn't affect them. Creatures that lived above the water were more affected because the NOx and CH4 reacted with the sunlight producing a deadly level of O3. .--Randana (talk) 05:11, 4 April 2012 (UTC)
- As said in the critique above there was still life after the Chicxulub. But the main animal many scientists are focusing on is the dinosaurs. Many mammals after the extinction were also able to dig under ground where they were lower levels of O3. Because of this humans were later able to evolve which was on Dinosaur week on Discovery. Without the extinction of the dinosaurs we would not have been able to exist because they ate mammals at a accelerated rate. Therefore evolving would have been out of the question.
And as said in my previous critique many animals that lived above ground would have starved to death do to the lack of food. If the sun was not able to get through the dust many plants would die; therefore the animals eating the plants would die and the food chain would continue to to be affected from then on.Sambo1428 (talk)
- This study does not prove that an asteroid didn't kill of the dinosaurs but that selected species were able to survive longer than others after the asteroid did hit. This is true for most disasters however, as those that are better adopted to the changing conditions will survive. So while this study can provide a partial objection it does not provide an absolute refutation.Alaxative (talk) 05:22, 12 April 2012 (UTC)
- Kikuchi, R., & Vannests, M. (2010). A theoretical exercise in the modeling of ground-level ozone resulting from the k-t asteroid impact: its possible link with the extinction selectivity of terrestrial vertebrates. Journal of Palaogeography, Palaeoclimatologym Palaeocology, 288(1-4), 14-23. Retrived on March 29th from, http://library.mtroyal.ca:2048/login?url=http://dx.doi.org/10.1016/j.palaeo.2010.01.027. /A critique of The Cretaceous-Tertiary mass extinction is due to the post-impact ozone conditions from the asteroid collision in the Yucatan Peninsula in northestern Mexico (The Chicxulub crater). Journal of Palaogeography, Palaeoclimatologym Palaeocology, 288(1-4), 14-23
Although it is believed that the meteorite is the major cause of the extinction of dinosaurs, critical evidence arose when a 50cm-thick laminated micritic and partially dolomitized limestone between the top of the impact breccia and a 1cm-thick green clay layer that marks the cretaceous-tertiary transition was observed. If the the meteorite caused the extinction of these dinosaurs, then this 50cm layer would have been impacted otherwise it would be finely laminated. The 50-cm layer observed was finely laminated which makes a good argument against the extinction of the dinosaurs as a result of the meteorite impact.