Where are we in this 62 million cycle?
Roper
. Interestingly they mention Planet X in it also. "With surprising and mysterious regularity, life on Earth has flourished and vanished in cycles of mass extinction every 62 million years, say two UC Berkeley scientists who discovered the pattern after a painstaking computer study of fossil records going back for more than 500 million years"
"We've tried everything we can think of to find an explanation for these weird cycles of biodiversity and extinction," Muller said, "and so far, we've failed."
But the cycles are so clear that the evidence "simply jumps out of the data," said James Kirchner
Perhaps, they suggested, there's an unknown "Planet X" somewhere far out beyond the solar system that's disturbing the comets in the distant region called the Oort Cloud -- where they exist by the millions -- to the point that they shower the Earth and cause extinctions in regular cycles.