Flea_Bit_Monkey
10-12-2006, 07:33 PM
Looks like God wipes the slate clean every 2.5 million years.
Linky (http://www.nytimes.com/2006/10/12/science/earth/12extinct.html?ei=5065&en=83d5e73f9f09c803&ex=1161316800&partner=MYWAY&pagewanted=print)
October 12, 2006
Study Links Extinction Cycles to Changes in Earth’s Orbit and Tilt
By JOHN NOBLE WILFORD
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.
It so happens, the paleontologists say, that variations in the course Earth travels around the Sun and in the tilt of its axis are associated with episodes of global cooling. Their new research on the fossil record shows that the cyclical pattern of these phenomena corresponds to species turnover in rodents and probably other mammal groups as well.
In a report appearing today in the journal Nature, Dutch and Spanish scientists led by Jan A. van Dam of Utrecht University in the Netherlands say the “astronomical hypothesis for species turnover provides a crucial missing piece in the puzzle of mammal species- and genus-level evolution.”
In addition, the researchers write, the hypothesis “offers a plausible explanation for the characteristic duration of more or less 2.5 million years of the mean species life span in mammals.”
Linky (http://www.nytimes.com/2006/10/12/science/earth/12extinct.html?ei=5065&en=83d5e73f9f09c803&ex=1161316800&partner=MYWAY&pagewanted=print)
October 12, 2006
Study Links Extinction Cycles to Changes in Earth’s Orbit and Tilt
By JOHN NOBLE WILFORD
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.
It so happens, the paleontologists say, that variations in the course Earth travels around the Sun and in the tilt of its axis are associated with episodes of global cooling. Their new research on the fossil record shows that the cyclical pattern of these phenomena corresponds to species turnover in rodents and probably other mammal groups as well.
In a report appearing today in the journal Nature, Dutch and Spanish scientists led by Jan A. van Dam of Utrecht University in the Netherlands say the “astronomical hypothesis for species turnover provides a crucial missing piece in the puzzle of mammal species- and genus-level evolution.”
In addition, the researchers write, the hypothesis “offers a plausible explanation for the characteristic duration of more or less 2.5 million years of the mean species life span in mammals.”