The Earth might have a "pulse" that causes extinctions every 60 million years

The Earth might have a "pulse" that causes extinctions every 60 million years | Digg Space:

'via Blog this'

Every sixty million years, the biodiversity of our planet's oceans mysteriously crashes. This strange boom and bust cycle goes back 500 million years, and we now might know why: rising continents make the oceans too shallow for species to survive.

The key to this mystery, according to new research led by University of Kansas physicist Adrian Melott, is the isotope strontium-87. This is one of four stable isotopes of the element strontium, although its less common (7.0%) than strontium-86 (9.86%) and much, much less abundant than strontium-88 (82.58%). The researchers, which also included paleontologist Richard Bambach and earth scientists Kenni D. Petersen and John M. McArthur, found that the concentration of Sr-87 relative to Sr-86 in marine fossils seems to increase every 60 million years, in lockstep with the periodic wave of extinction.