when did dinos exist

[troodon]

But what is your opinion on the asteroid theory then? smashing good theory?

The asteroid definatly had something to do with the extinction. It's silly to think it was just a coincidence that an asteroid impacted just after the dinosaurs went extinct. But the asteroid definatly doesn't explain all of it. The dinosaurs thrived right on through at least 3 similarly sized impacts during their tenure on earth and were just fine. So we are left with some options.

1) There was something about the previous impacts that minimalized their affect on the dinosaurs. This was not the case with the K/T impact.

2) There was something about the K/T impact that made it particularly harmful to the dinosaurs. This was not the case with the previous impacts.

3) The K/T impact would not have killed off the dinosaurs were it not for contributing factors. Dinosaur diversity appears to have dropped very sharply right before the impact. Small diversity is not good for surviving huge disasters. What caused this drop in diversity could have been anything; from disease to vulcanism to just plain old natural selection.

One problem with theorizing that the asteroid was the main cause is that so many animals that are somewhat similar to dinosaurs (fresh water crocs in size and birds in aerobic activity) made it through fine. I think it is a safe bet that the dinosaurs were having big problems and the asteroid added too much insult to injury.

But, it should be noted, this was the second biggest die off in earth's history. Fish died off, crocodiles died off, toothed birds and many untoothed birds died off. This cannot be explaned without some sort of global catastrophe.