h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Wasn't it One of the Alverez's who put forward the meteor/comet impact theory and went round trying to find a suitable crater - ie the one off the Yucatan Peninsula. I'll have to do some more research to check, but thought I'd point it out.

Ok just done a check and it was both father and son (Luis and Walter Alvarez) along with Frank Asaro and Helen Michael - though it's generally the Alvarezes who get the fame . They put forward the theory that a large impact from space caused the huge rise in levels of Iridium in the clay at the cretaceous/tertiary boundry layer.

A more serious issue, studies of air bubbles in amber laid down before and after the kt accident show only half as much oygen in the air afterward as before.

Something happened to about half the total oxygen in the air, and its loss, more than any other single factor, is probably the cause of the mass extinction.