Also, what exactly cuased the dinsaurs to go extinct? I watched a TV show which stated that disease may have been the culprit.
Dinosaurs were almost certainly wiped out by a large asteroid hitting in what is now the Yukutan penninusula. It didn't just wipe out the dinosaurs, either, it also caused the extinction of several other major groups of large reptiles (actually all but one or two), several smaller groups of birds and mammals, a number of fish groups, and numerous invertebrates and plants. All in all about 50% of genera went extinct, if I recall correctly. The only groups that seems to have done well out of all this are fungus, which fed on the decaying matter, and ferns, which were able to quickly establish themselves when competing plant life was wiped out.
See here:
http://en.wikipedia.org/wiki/Chicxulub_craterAlthough technically dinosaurs aren't instinct, birds are actually a type of therapod dinosaur (same group that T-rex and velociraptor belonged to).
It definitely could not have been a disease, there is no way a disease could wipe out such diverse groups of organisms as dinosaurs, ammonites, and various plants while sparing closely-related organisms like birds, the nautilus, and ferns. Also, the pattern of extinction, particularly the much larger extinction faced by marine organisms using calcium carbonate shells, while similar organisms that does not make carbonate shells were much less affected, indicate that there was a major ocean acidification event that would have seriously disrupted marine food chains (the ability to make carbonate shells is extremely dependent on ocean acidity, and many groups of plankton make such shells).
Another popular hypothesis is that it was the result of one of the larger volcanic events in the planet's history, the Deccan traps event, but that events continued for hundreds of thousands of years yet the actual extinction event appeared to occur at least couple orders of magnitude more quickly. Also, I read an article recently stating that it would probably have not caused the sudden spike in ocean acidity that would have been required to kill of the carbonate-using marine life.
Speaking of birds and mammals, interestingly birds were actually the most successful group after the dinosaurs went extinct. They were able to quickly evolve large meat-eating versions that were the dominant carnivores at the time and were remarkably similar to meat-eating dinosaurs (although no where near as big). Some even developed claws on their front limbs to help them hunt. Ultimately mammals evolved their own carnivores that proved to by more successful long-term, but the last really large (several yards tall) carnivore birds died out in the Americas only a little while before the first human settlers arrived.
Topic: Halbred's Paleo-News Thread (Read 118395 times)
