This page is a mirror of the original page found on Dinosauria On-Line . For this page and more, visit today. The leading candidate as the site of this impact is the Chicxulub impact crater on the tip of the Yucatan Peninsula.
Iridium is rare on earth but common in extra-terrestrial bodies, such as asteroids.
If the impact occurred and caused the acid rain suggested by the models it is not hard to see why a bone spike would be the last thing that you would expect to find. Consider for a moment the boundary clay. What ever produced that had to erode many rocks to produce that clay everywhere we see the boundary. That sort of erosion implies very large quantities of very acidic water falling out of the sky. Now consider the average bone.