Jump to content




Welcome to Unexplained Mysteries! Please sign in or create an account to start posting and to access a host of extra features.


- - - - -

Earth "wobbles" Linked to mammal extinctions


  • Please log in to reply
6 replies to this topic

#1    Avinash_Tyagi

Avinash_Tyagi

    Government Agent

  • Member
  • 3,871 posts
  • Joined:19 Mar 2006

  • Searching For Answers

Posted 12 October 2006 - 04:39 PM

Sci-Am

Mammal species do not seem to last very long in the grand scheme of things, persisting for an average of 2.5 million years, according to the fossil record. By studying the fossilized teeth of rodents over a span of 22 million years, Jan van Dam of Utrecht University in the Netherlands and his colleagues confirmed this cycle of rodent species rise and fall. But they also found that it closely matched variations in Earth's orbit--and may have definitively linked the two. "If you have seven or eight of these in a row all showing the same pattern, it becomes extremely unlikely that it can be reduced to chance," explains paleoecologist Paul Olsen of Columbia University.

By looking at more than 80,000 teeth personally collected or published in others’ work, van Dam and his colleagues were able to create a database of 132 rodent species that lived on the banks of ancient rivers, streams and lakes in what would become Spain. They compiled a timeline, checking in every 100,000 years, to determine when these species arose and died out as well as when the greatest number flourished. Species that disappeared for more than one million years were counted as extinct. Analyzing this timeline, they found that the birth and death of these species closely overlapped in time and clustered around specific cycles at one million and 2.4 million years.

These cycles of origination and extinction correlate closely with known astronomical cycles: a 2.37-million-year cycle between an elliptical and circular orbit and a 970,000-year change in the tilt of Earth's axis. The two combine to create periods in which our planet did not tilt very much as it revolved around the sun, thereby eliminating seasons and resulting in less climatic variability. "The lack of warm high-latitude summers--normally associated with extreme eccentricity and obliquity--results in ice expansion on Antarctica, and later the high northern latitudes as well, which will affect the rest of the world's climate resulting in cooling and changes in precipitation patterns," van Dam says. "These climate changes may destroy the habitat of rodents or give new rodent forms a chance."

The paper presenting this finding, published in Nature on October 12, is the first detailed evidence of such a linkage, although it has been suspected in the past. The fossil record for other types of animals is more difficult to work with; for example, lizards lack the clear differences in tooth structure that help delineate rodent species, and insects notoriously fail to fossilize regularly. "We're left with just a few groups," Olsen says. "My own research has focused on fish and fossil pollen spores, and they show exactly these kinds of patterns." Van Dam and his team plan to expand their search into other animal groups to look for the same patterns. "Paleoceanographers found indications for climate change--cooling--at these types of configurations in deep sea cores," he notes.

At present, Earth is in a period of axial tilt and an elliptical orbit, a recipe for climate shifts but relatively stable mammal populations. But such periods in the past have not included such high levels of greenhouse gases in the atmosphere, and that is driving an unprecedented--an unpredictable--climate change. "There is no precedent for it in any of the other previous cycles that are well documented," Olsen adds. That may shorten the life span of mammal species presently on the planet.


Spider-pig, Spider-pig, does whatever a Spider-pig does   Homer Simpson

Everyday the cafe's and and outdoor markets of the middle east explode in anticipation! -Aasif Mandvi

Vir!  Intelligence has no place in politics! Londo Mollari

WWBD: What Would Belldandy Do?

When Christians attack!:

#2    Lizardian_guy

Lizardian_guy

    Apparition

  • Member
  • PipPip
  • 319 posts
  • Joined:19 Sep 2006
  • Location:Undefinable variable entered, system failure imminent. Please contact your administrator.

  • I think, therefore I am. Does this mean I can discard the existence of mankind?

Posted 12 October 2006 - 07:02 PM

One note to anyone reading this:

A correlation has been observed, not a link. Big difference.

The most merciful thing in the world, I think, is the inability of the human mind to correlate all its contents.
~ Howard Phillips Lovecraft

Trying to explain the unknown as the work of God is equally stupid as trying to explain it as the work of the human mind.
~ Myself

#3    Avinash_Tyagi

Avinash_Tyagi

    Government Agent

  • Member
  • 3,871 posts
  • Joined:19 Mar 2006

  • Searching For Answers

Posted 12 October 2006 - 08:40 PM

Quote


One note to anyone reading this:

A correlation has been observed, not a link. Big difference.



Correction, a Correlation does indicate a link, just not causation thumbsup.gif

Spider-pig, Spider-pig, does whatever a Spider-pig does   Homer Simpson

Everyday the cafe's and and outdoor markets of the middle east explode in anticipation! -Aasif Mandvi

Vir!  Intelligence has no place in politics! Londo Mollari

WWBD: What Would Belldandy Do?

When Christians attack!:

#4    frogfish

frogfish

    ஆங்கிலத்த&

  • Member
  • 11,142 posts
  • Joined:19 Sep 2005
  • Gender:Male
  • Location:The Swamp

  • Flyfishing -- the Art of the Gods



Posted 12 October 2006 - 10:46 PM

Correlation, but no cause.

-Frogfish-
Posted Image
Researcher-Prostate Cancer Oncogene Research
University of Michigan Comprehensive Cancer Center

The National Center for Biotech Information
My Photo Gallery: Capturing India

Fishing is a Way of Life!


#5    positron

positron

    Apparition

  • Member
  • PipPip
  • 355 posts
  • Joined:02 Jun 2006
  • Gender:Female
  • Location:New York

  • I believe that aliens do exist among us.

Posted 13 October 2006 - 03:31 AM

Quote


Correlation, but no cause.

Why dosen't  anyone discuss the fact that we are all hanging upside down,every day ?The earth is round after all ! I can't believe that this is not a topic of conversation.


#6    ShaunZero

ShaunZero

    Non-Corporeal Being

  • Member
  • 8,339 posts
  • Joined:13 May 2005
  • Gender:Male

Posted 13 October 2006 - 03:42 AM

Well... We're not upside down. Direction comes from only our perspective due to gravity. Down is the direction gravity is pulling, so actually we're right side up.

"What if there were no hypothetical questions?" ~ George Carlin
Are you a cynic?

#7    frogfish

frogfish

    ஆங்கிலத்த&

  • Member
  • 11,142 posts
  • Joined:19 Sep 2005
  • Gender:Male
  • Location:The Swamp

  • Flyfishing -- the Art of the Gods



Posted 13 October 2006 - 08:43 PM

Quote

Why dosen't anyone discuss the fact that we are all hanging upside down,every day

Depends on perspective...The universe has infinite direction.

-Frogfish-
Posted Image
Researcher-Prostate Cancer Oncogene Research
University of Michigan Comprehensive Cancer Center

The National Center for Biotech Information
My Photo Gallery: Capturing India

Fishing is a Way of Life!





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users