Re: Fossil Records Show Biodiversity Comes and Goes

From: George (george_at_wtfiswrongwithyou.com)
Date: 03/15/05 

Date: Tue, 15 Mar 2005 05:03:42 GMT

"snex" <snex@comcast.net> wrote in message
news:1110860720.852136.76130@g14g2000cwa.googlegroups.com...
>
> John Harshman wrote:
>> George wrote:
>>
>> >
> http://www.lbl.gov/Science-Articles/Archive/Phys-fossil-biodiversity.html
>> >
>> > BERKELEY, CA - A detailed and extensive new analysis of the fossil
> records of
>> > marine animals over the past 542 million years has yielded a
> stunning surprise.
>> > Biodiversity appears to rise and fall in mysterious cycles of 62
> million years
>> > for which science has no satisfactory explanation. The analysis,
> performed by
>> > researchers with the U.S. Department of Energy's Lawrence Berkeley
> National
>> > Laboratory (Berkeley Lab) and the University of California at
> Berkeley, has
>> > withstood thorough testing so that confidence in the results is
> above
>> > 99-percent.
>>
>> Grain of salt time: it was this same database in a slightly earlier
>> incarnation that was said to have displayed a 32-million-year
>> periodicity in extinctions. There is still considerable argument
> about
>> whether that cycle exists. Now we have one that's just about twice as
> long.
>
> i heard (from a bbc special i think) that they coincided with the sun's
> passage through the central area of the arm of the milky way, which
> caused comets from the oort cloud to get hurdled toward the sun. is
> there any validity to this?

It's just one of several hypotheses.

Relevant Pages

  • Re: Fossil Records Show Biodiversity Comes and Goes
    ... >> researchers with the U.S. Department of Energy's Lawrence Berkeley ... >What about the cretaceous and permian mass extinctions? ... of the way fossils are preserved means that the record is intermittent. ... any knows no cyclic nature to extinctions nor of any evidence of mass ...
    (sci.geo.geology)
  • Re: Spiral Arm Crossings and Mass Extinctions
    ... >> periodicity are not fully related. ... > number of mass extinctions, and the causative mechanisms that the "arm ... > techniques were developed from and by astronomers studying heavenly ... the path of massive radiation discharges from various astronomical sources. ...
    (sci.geo.geology)
  • Re: Fossil Records Show Biodiversity Comes and Goes
    ... stunning surprise. ... >> for which science has no satisfactory explanation. ... Berkeley, has ...
    (sci.geo.geology)
  • Re: Spiral Arm Crossings and Mass Extinctions
    ... this is a divergance; my real point is that asteroids and ... > periodicity are not fully related. ... number of mass extinctions, and the causative mechanisms that the "arm ... dodos became extinct because of astronomical bodies. ...
    (sci.geo.geology)
  • Re: Fossil Records Show Biodiversity Comes and Goes
    ... George wrote: ... >>stunning surprise. ... >>Berkeley, has ... >>passage through the central area of the arm of the milky way, ...
    (sci.geo.geology)