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Thread: Descent of Birds

  1. #1 Descent of Birds 
    SHF is offline
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    Is it odd that birds descend from saurischia (lizard hipped) and not ornithischia (bird hipped)?

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  3. #2  
    Forum Professor Zwirko's Avatar
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    It's probably a case of convergent evolution of hip structures and an historical accident of terminology (my guess).

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  4. #3  
    Moderator Moderator Cogito Ergo Sum's Avatar
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    Quote Originally Posted by Zwirko View Post
    It's probably a case of convergent evolution of hip structures and an historical accident of terminology (my guess).

    Your guess is correct:
    "Oddly, birds are derived from the "lizard-hipped" dinosaurs and not from the "bird-hipped" ornithiscian dinosaurs. The "bird-hipped" condition of a pubis pointing toward the back of the animal occurred twice independently, once in the ornithischians and once in the lineage leading to birds, an example of convergent evolution. Thus "ornithischia," taken literally, is a misnomer, since the ornithischians have ornithischian-like pelves, not bird-like. Only birds (and their immediate ancestors) have bird-like pelves."

    The Saurischia
    "The only safe rule is to dispute only with those of your acquaintance of whom you know that they possess sufficient intelligence and self-respect not to advance absurdities; to appeal to reason and not to authority, and to listen to reason and yield to it; and, finally, to be willing to accept reason even from an opponent, and to be just enough to bear being proved to be in the wrong."

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  5. #4  
    WYSIWYG Moderator marnixR's Avatar
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    and as with many characteristics, dromaeosaurs have modified the saurischian pelvis to become more bird-like :

    The dromaeosaur pubis ornithischian saurischians
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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