Extinction caused by changes in earth'r rotation tilt?

No big meteorite striking Earth anymore then? What do we make of the iridium stratus in Gubbio, then?

wait a minute, the paper is talking only about mammals: If rodents in Spain are any guide, periodic changes in Earth’s orbit may account for the apparent regularity with which new species of mammals emerge and then go extinct, scientists are reporting today.

and it only consider the last 22 million years... So, BIG catastrophic extinction are safeguarded. The one they're talking about now are 'single species' extinctions, explaining the already known average period of 2.5My for a single species' time on Earth. you know, Australopithecus isn't here anymore, same for prehistoric horses and so on... nothing so exciting...

anyway, one more piece of the puzzle slots in.

cheers...