DesertFox
10-12-2006, 07:08 PM
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.
More (http://www.nytimes.com/2006/10/12/science/earth/12extinct.html?ei=5065&en=83d5e73f9f09c803&ex=1161316800&partner=MYWAY&pagewanted=print)
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.
More (http://www.nytimes.com/2006/10/12/science/earth/12extinct.html?ei=5065&en=83d5e73f9f09c803&ex=1161316800&partner=MYWAY&pagewanted=print)