[AlbertWang]

OK, I'm not so bright, but the Dino's went AWOL 65 million years ago, and now these folks claim the crater is 300,000 years older than that.......hhhmmm.... let's figure this in our head....... 10% of 65 million is 6.5 Million, 1% would be 0.65 million, so 300,000 years is like one half of one percent of the time in question.

Yeah, right, we can pinpoint this to one half of one percent.

[FourPeas]

If I read the article correctly, the layer of clay seems to be the critical determinant.