http://www.cnn.com/2004/TECH/science/03/02/coolsc.dinosaurs.extinction/index.html
Is the asteroid wiping out dinosaurs a convenient story?
Is the asteroid wiping out dinosaurs a convenient story?
Asteroid wipeing out dinosaurs, a story??
Peter Jenkins
Muse
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It's a 'theory'. One which may prove to be wrong, or partly wrong................. It's not like it's written in some holy book or something...................
P
P
Hexxenhammer
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I don't know that anyone ever claimed that the asteroid was the end all be all of why the dinosaurs died off. Of course there's going to be more going on than 1 single thing. The asteroid coupled with increased volcanic activity, coupled with seperate continents coming together allowing the spread of disease, etc, etc, is a more comprehensive theory.
Tricky
Briefly immortal
For a lot of non-scientific people, it is easier to envision a big asteroid hitting and all the dinosaurs falling over dead. Paleontologists know that this is a great oversimplification. But it is pretty certain that the asteroid hit, and it is pretty certain that there were mass extinctions across the Cretaceous/Tertiary boundary in a period of time that is, relative to geologic time, nearly instantaneous.
Of course, there were big environmental changes, principally the climate, but also "pollution" from the vaporized meteor and impact site. At this time, selective pressure was extremely high, and speciation occured at a very rapid rate. Many "new" species also arose at this time. The author correctly points out that dinosaurs did not die. We still have them around, except we call them "birds".
However, it is relatively certain that the meteor impact was the dominant factor in the mass extinction of so many species (not just dinosaurs).
I was a geology student in the late 70's when this theory was just beginning to gain support. It was still considered "out there" by a lot of the geologic community because we had no evidence of a meteor impact. The clincher was the discovery of high levels of iridium, an element much more common in asteroids than on earth, at Cretaceous/Tertiary boundry sediments practically world-wide, consistant with the vaporization of an asteroid when it impacted the earth. We see the same thing around places like Meteor Crater Arizona. The impact was not the only factor, and certainly the dinosaurs did not die/evolve overnight, but the impact was certainly the dominant cause.
This is actually a great example of scientific skepticism doing its job.
Of course, there were big environmental changes, principally the climate, but also "pollution" from the vaporized meteor and impact site. At this time, selective pressure was extremely high, and speciation occured at a very rapid rate. Many "new" species also arose at this time. The author correctly points out that dinosaurs did not die. We still have them around, except we call them "birds".
However, it is relatively certain that the meteor impact was the dominant factor in the mass extinction of so many species (not just dinosaurs).
I was a geology student in the late 70's when this theory was just beginning to gain support. It was still considered "out there" by a lot of the geologic community because we had no evidence of a meteor impact. The clincher was the discovery of high levels of iridium, an element much more common in asteroids than on earth, at Cretaceous/Tertiary boundry sediments practically world-wide, consistant with the vaporization of an asteroid when it impacted the earth. We see the same thing around places like Meteor Crater Arizona. The impact was not the only factor, and certainly the dinosaurs did not die/evolve overnight, but the impact was certainly the dominant cause.
This is actually a great example of scientific skepticism doing its job.
The idea that a large bolide impact was the chief cause of the Cretaceous-Tertiary boundary extinction is consistent with many observations. Some geologists, such as Gerta Keller, argue that it is not sufficient. So there is legitimate debate amongst geologists over this issue. Some creationists interpret this to mean that "evolutionary theory is in trouble"--but additional evidence may yet provide more certainty.
Skeptical Greg
Agave Wine Connoisseur
We'll probably know more about it after the next one hits..
Get back to us then Tai'....
P.S.
Change ' story ' to ' theory '...
Yes, it is just a theory... You might want to revisit the definition of ' theory '..
You won't find anything like: " ... probably not true .. "
Get back to us then Tai'....
P.S.
Change ' story ' to ' theory '...
Yes, it is just a theory... You might want to revisit the definition of ' theory '..
You won't find anything like: " ... probably not true .. "
Hexxenhammer
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Anytime scientists have any disagreement about anything relating to evolution, geology, extinction, etc the creationists take that as proof that evolutionary theory is in trouble.Phaycops said:
Just out of curiosity, how does this argument go?
Just to clarify: Additional evidence may lend greater support to the mass extinction by bolide impact idea, or may give greater credence to some other theory such as environment-altering emanations from massive lava flows. In any case, the current debate among geoscientists is about a mechanism of apparent mass extinction, not about evolution. Furthermore, the debate revolves around various pieces of evidence (such as geochemical and mineralogical evidence); the idea was not pulled out of thin air (ie, not a "Just-So Story").
(And thanks, Hexxenhammer, that's exactly right.)
(And thanks, Hexxenhammer, that's exactly right.)
neutrino_cannon
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In addition to what Tricky said, there are a number of problems with an asteroid impact killing off the dinosaurs:
1) Why didn't the asteroid kill off the frogs and turtles? It should have, if it killed by generally disrupting the food chain. Turtles have got to eat too you know. No small cold blooded species that I'm aware of went extinct as a result of the KT boundry "event".
2) If the asteroid killed of the mosasaurs, et al, who also dies out at the same time, then does this mean that the effect was great enough to destroy aquatic communities? If so, then why didn't all the fish die off?
3) If the asteroid killed off the mosasaurs and most other aquatic reptiles, then how come several genera of marine crocodile did not go extinct, and in fact flourished well into the cenozoic?
4) While many avian groups of the late cretaceous suffered quite nasty losses at the KT boundry (for some reason, all the toothed birds died off), they were not killed off. Same goes for mammals, while many groups of mammals were hit hard too, notably the marsupials, these small warm blooded animals, dependant on a huge (for their size) food source did not die off when the food chain was completely destroyed by asteroidal dust. Hmm... While it can be argued that mammals and birds of the time would be hard to kill off because they reproduced quickly, and were small compared to modern forms (the largest mammals and birds being cat and hawk sized respectively), this arguement ignores one critical component. Dinosaurs would have been hard to kill off too. Of all the dinosaur nest we know, all dinosaurs, even the really big ones (titanosaur nests are well known from patagonia) laid huge clutches. From their bone structure, they grew incredibly quickly too. The dinosaurs, especially the smaller therapods and ornithopods ould have been incredibly hard to kill off.
1) Why didn't the asteroid kill off the frogs and turtles? It should have, if it killed by generally disrupting the food chain. Turtles have got to eat too you know. No small cold blooded species that I'm aware of went extinct as a result of the KT boundry "event".
2) If the asteroid killed of the mosasaurs, et al, who also dies out at the same time, then does this mean that the effect was great enough to destroy aquatic communities? If so, then why didn't all the fish die off?
3) If the asteroid killed off the mosasaurs and most other aquatic reptiles, then how come several genera of marine crocodile did not go extinct, and in fact flourished well into the cenozoic?
4) While many avian groups of the late cretaceous suffered quite nasty losses at the KT boundry (for some reason, all the toothed birds died off), they were not killed off. Same goes for mammals, while many groups of mammals were hit hard too, notably the marsupials, these small warm blooded animals, dependant on a huge (for their size) food source did not die off when the food chain was completely destroyed by asteroidal dust. Hmm... While it can be argued that mammals and birds of the time would be hard to kill off because they reproduced quickly, and were small compared to modern forms (the largest mammals and birds being cat and hawk sized respectively), this arguement ignores one critical component. Dinosaurs would have been hard to kill off too. Of all the dinosaur nest we know, all dinosaurs, even the really big ones (titanosaur nests are well known from patagonia) laid huge clutches. From their bone structure, they grew incredibly quickly too. The dinosaurs, especially the smaller therapods and ornithopods ould have been incredibly hard to kill off.
Hexxenhammer
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And only creationists would extrapolate a disagreement about geology into one about evolution. To them, any astronomical, biological, and geological change means "evil-you-shun".me said:
Hexxenhammer
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I know. It's ok. It's not your fault the creationist morons don't know know their @sses from a crater in the ground.Phaycops said: