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Horizon

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  • Paul Andrew King
    I ve just finished watching this evenings Horizon on BBC2. The subject was the changing views on the vertebrate move from water to land - and the new evidence
    Message 1 of 1 , Feb 1 2:28 PM
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      I've just finished watching this evenings Horizon on BBC2. The
      subject was the changing views on the vertebrate move from water to
      land - and the new evidence that has come to light over the last ten
      years. Until relatively recently all we had was a very good
      candidate for the fish end of the transition - Eusthenopteron and one
      fossil of a very early tetrapod - Icthyostega. Recently more fossils
      of Devonian tetrapods, such as Acanthostega have been found.

      The most important points were :

      1. The pentadactyl (five-fingered) limb appears after the transition.
      The earliest tetrapods had more toes.

      2. Legs developed for movement in WATER - probably for moving amongst
      the abundant plants. The earliest tetrapods have gills and legs that
      angled wrongly for walking on land.

      3. Very recently an obscure fossil was reexamined. It was a section
      of jaw which turned out to be morphologically intermediate between
      fish and tetrapods. Even though it is likely to be a side-branch
      rather than a direct ancestor of ours it is the first fossil showing
      this particular transition. (Although the indirect evidence strongly
      supported the relationship).


      Duane Gish appeared on the program although I doubt that he will be
      very pleased with it. He was only shown to emphasise that there are
      people who will exploit the lack of fossils to try to suppress
      evolution. Gish played no part in the main story. It would have
      been interesting to see his reaction on being told that a new
      transitional fossil had been found but I doubt that it would have
      made good television.
      --
      --
      "The T'ang emperors were strong believers in the pills of
      immortality. More emperors died of poisoning from ingesting minerals
      in the T'ang than in any other dynasty" - Eva Wong _The Shambhala
      Guide to Taoism_

      Paul K.
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