Fossils don't form every single time a creature dies. If my dog buries his bone is my back yard, it's not too likely it'll become a fossil.|
Reply #2. Mar 05 10, 4:39 PM
Dinosaurs were not the only major species wiped out by the KT event. Roughly half of the animal species on the planet died during that period.|
Dinosaurs merely happen to be the largest, so their bones are easier to find that anything else.
Reply #3. Mar 05 10, 4:55 PM
Well, it's true that most dead animals don't become fossils. But it's also true that more dead dinosaurs = more fossils, all things being equal. So we should see a spike in the number of dinosaur fossils at the KT boundary, and we don't. If you think about it, the rate of fossilization should have increased, because there would have been fewer large predators to scavenge the corpses of dead dinosaurs before they were buried. Just a thought.|
Reply #4. Mar 05 10, 5:34 PM
Interesting link - although I have to say some of the responses to it were more fun to read - I love it when 'the scientists know nothing' brigade come out to play. :-)|
It's an interesting article, and I'd have to say from the little I have read on the subject it seems like a plausible theory. I do shudder a little at things like 'official'. It's best guess like a lot of other science - which I think is a good thing. Forming a theory, questioning it again and again is surely what yields the best results.
Reply #5. Mar 06 10, 5:04 PM
Well, take into consideration the fact that our planet is very good at concealing evidence of its own history. The fossil record is one of the most misunderstood fields of science. It can't explain alone where all the creatures of the Cretaceous went any more than it can explain the origins of the human species. Looking at the fossil record alone is like looking through a very muddy piece of glass - you shouldn't expect to see enough of any picture to come to any decent conclusion. I have a great deal of respect for those paleontologists who actually manage to discern one species from another after so many millions of years.|
But the fact is that if you really want a clear picture of what the Earth was like millions of years ago, you have to go to other fields of science - physics, genetics, chemistry, geology, and so forth. We have at least one impact site that we can prove could have wiped out mcuh of the planet's life forms alone. Whether or not the thing that hit the Earth 65 million years ago was one object or a string of impacts (like Shoemaker-Levi 9 which hit Jupiter 20 years ago) is unknown. We have some evidence in geology about other possible contributing factors like volcanic activity (which would have been exacerbated by the impact if anything), but there is no evidence that says that aside from the impact anything was really amiss in the world 65 million years ago.
If we find a man dead in the street one day with a bullet in his heart, and then take him to the autopsy room where the medical examiner finds a rare but mild skin condition, it's still a leap of faith to say that the skin condition is what killed him. Same thing with solving the mysterious deaths of 75% of the world's species with an impact site and some volcanic sputterings. We will never know exactly how it all played out, but there was a collision between at least one large object and the Earth 65 million years ago, which set off a series of events that led to the extinction of over half the world's species of life. Why the other half survived is something of a mysetery, but I'm guessing part of it had to do with the fact that most of the survivors were scavengers and that suddenly there were a lot of really big carcasses lying around waiting to be eaten.
Reply #6. Mar 06 10, 9:25 PM
There's no doubt there was a major asteroid impact about the time the dinosaurs died out. But the impact theory has a lot of holes in it. There is some evidence that dinosaurs were on the way out before the asteroid struck; fewer species are found just below the KT boundary. Could have been a virus, could have been climate change, who knows? It's just very strange that every single species of dinosaur died out, but not other animals (crocodilians, for example), did not.|
Reply #7. Mar 07 10, 3:03 AM
Could have been little men from Mars... |
Reply #8. Mar 07 10, 5:38 AM
Ice core data stretching back around 420,000 years shows a cyclical variation in temperature and carbon dioxide levels, so the ambient temperature can vary up to 10 degrees in a few millenia. It seems likely that a natural but more severe than usual drop in temperature during one of these cycles was causing a decline in the population of cold-blooded creatures like dinosaurs, and maybe a meteor strike caused a temporary global winter for a decade or two that finished off the rest. We will never know unless we can get ice cores stretching back millions of years.|
Reply #9. Mar 07 10, 6:15 PM
It's only official until the next scientist gets another research grant on the subject! |
Reply #10. Mar 20 10, 9:19 AM
OoooH! Starlord,you sound as cynical as me!
As I've always said,never trust a man that calls himself 'An expert'! Unless they were there.......!
Reply #11. Mar 20 10, 9:41 AM
Experts are just people who are paid to give there opinion on a subject.|
Reply #12. Mar 20 10, 2:30 PM
The Earth's not flat?
Us humans have been here longer than 6,000 years?
Dinosaurs weren't hunted to extinction (like the Moa) by our 6,000year old ancestors?
Awww I've been robbed!
Reply #13. Mar 23 10, 9:44 PM
There's a lot of evidence for more than just a comet or asteriod impact. In India, scientists found evidence for massive amounts of volcanic activity. Perhaps this mass extinction was caused by a combination of both events.|
Reply #14. Jun 29 12, 2:15 AM
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