The question of non-bird dinosaur
extinction is really an open one, I mean certainly that there's a tremendous
amount of evidence, in fact that there's no doubt that at the time the dinosaurs went extinct a large meteorite or asteroid hit the
planet somewhere off the Yucatan Peninsula in Mexico. However, directly tying this event to the disappearance of the terestrial fauna is very difficult and that's just because our sample is so
small there's only a couple places in the world
where both dinosaur fossils as well as evidence of the impact are preserved both of those are in western North America, so we don't know whether it was an
instantaneous event we don't know whether the dinosaurs in
the southern hemisphere, like held on for millions of years afterwards, we just
don't have the record to be able to determine that. One thing we do know though, is that certainly that the dinosaurs, non-bird dinosaurs appear to be coming more and more rare, less common as you approach the time when the meteroite hit about
sixty five point four million years ago so that it's not like everything was
going great, and then you just had this massive cataclysmic
event and everything disappeared, we know that stuff was changing, stuff
was changing quickly. At the same time there was a huge amount of volcanic activity especially from places in
western India, and interestingly enough this coincides with around the time of
the asteroid impact so many paleontologists feel that it was a combination of
factors, maybe both asteroids and volcanos that did the non-bird dinosaurs in,
and I should emphasize not just that non-avian or non-bird dinosaurs but
many many other animals and plants, in fact we estimate that maybe as much as seventy-five percent of
all the species that lived on the earth at that time went extinct during this
very dramatic event.