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Dino 'survival' claim disputed (BBC News Online)

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  • npat1@juno.com
    Will we ever know for sure what all happened to the dinosaurs? The uncertainty out the need for action to reduce greenhouse gas emissions well before all come
    Message 1 of 1 , Feb 5, 2004
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      Will we ever know for sure what all happened to the dinosaurs?
      The uncertainty out the need for action to reduce greenhouse gas
      emissions well before all come to agreement on what will happen, because
      agreement may never come.


      Dino 'survival' claim disputed
      By Paul Rincon
      BBC News Online science staff

      The idea that dinosaurs survived for some time after the asteroid impact
      for wiping them out 65 million years ago has been dealt a blow. Dinosaur
      egg fragments dug out of rocks in China seem to postdate the dramatic
      extinction event popularly believed to have extinguished the creatures.

      But new data suggests the egg pieces got mixed up in later deposits
      through the
      action of mud and debris flows.

      Details of the latest findings are published in the Journal of Geology.

      Dinosaurs survived until the end of the Cretaceous Period of Earth
      history. But
      by the beginning of the Tertiary Period, about 65 million years ago, they
      apparently vanished.

      Egg discovery
      At numerous sites around the world, a clay layer separates rocks laid
      down in the Cretaceous from those deposited in the Tertiary. This is
      known as the K-T boundary.

      The boundary contains high concentrations of the element iridium,
      commonly found
      in meteorites. Researchers have proposed that a meteorite impact which
      a huge crater at Chicxulub in Mexico, could have been responsible for the
      of the creatures.

      Discoveries of dinosaur egg fragments in deposits from Nanxiong Basin,
      China, which contain Tertiary animal remains and pollen, suggested
      there could have survived until about 62 million years ago.

      But US and Chinese researchers now dispute this. They claim the egg
      pieces originated in Cretaceous deposits and were swept up in mud and
      debris flows during the Tertiary. This jumbled material was then

      Dr Brenda Buck of the University of Nevada, Las Vegas, US, said she came
      upon the idea while examining palaeosols, ancient soils that have been
      buried and later exposed in Nanxiong.

      "During the dry season you had these big open cracks," she explains.
      "Mudflows would come down and fill in those cracks. All those mudflows
      are in the [rock] sections where the flora and fauna are mixed."

      Dr Buck suggests the presence of several iridium layers at Nanxiong
      supports a view that Cretaceous rocks were reworked in the Tertiary.

      Multiple claims
      There have been other claims for the survival of dinosaurs into Tertiary
      times at sites in Montana and New Mexico in the US, in Bolivia and in

      All of these claims have been questioned by other researchers.

      "The only really well documented dinosaur remains are from the American
      west. We
      actually have no idea what's happening anywhere else in the world," Dr
      Norman MacLeod, keeper of palaeontology at the Natural History Museum in
      London, told BBC News Online.

      "We know that they lived on other continents, so there's no particular
      reason to suppose that that western US population was the last

      "It could well be that they went above the K-T boundary in other parts of
      the world, especially parts that were remote from the Chicxulub impact."

      Story from BBC NEWS:

      STEPHAN PICKERING / Chofetz Chayim ben-Avraham
      The Dinosaur Fractals Project
      2333 Portola Drive # 4
      Santa Cruz, California 95062-4250 USA
      website: http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology
      theropod research summarized: <www.dinodata.net>
      see under PICKERING at their Reference Base

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