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Thread: I want to have a science discussion or two...or many!

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  1. #20
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    Penguins evolved from an ancestor that was capable of powered flight.
    So was that ancestor a bird?

    If we track down the earliest "bird" capable of powered flight, we will almost certainly find that it evolved from an ancestor that was capable of lesser forms of air travel like gliding and parachuting. It's possible in theory to trace this all the way back to Archaeopteryx, where we will see that Archy is an ancestor to contemporary birds.

    We can argue all day about whether Archy was a bird or a dinosaur or something else --- it does have more in common with dinosaurs than with birds --- but this does not preclude it from being ancestral to birds. To put it this way; if you follow the chain far back enough, you will find that birds have a common ancestor which is not a bird, an ancestor they will share with another, broader taxonomical group of animals. So whether or not Archy is a "bird" by today's definition of a contemporary bird, it is still capable of being ancestral to contemporary birds. I don't get what's so hard to understand about that.

    And if you're thinking of Protoavis, that's another species that was thought to be a feathered bird predating Archy. But it was assembled from many different archeological sites, poorly organized, and is generally thought to be unreliable in any real detail, and so in the mainstream scientific community, it wasn't enough to dethrone Archy as the "oldest ancestral bird."

    My sources are contained in here. I'm pretty sure I posted the link to it and mentioned what it was earlier in the thread. http://melyssathepunkrocker.devianta...91590#/d4jour3
    That's just the video you posted earlier. Where were your sources for making that video?

    EDIT: The closest thing I can find to an example of what you might be talking about is this article from Nature.com (I found it with google and 5 seconds), which mentions other ancestral birds besides Archy:

    The fossil that is driving the latest Archaeopteryx rethink is called Xiaotingia zhengi, and is described in Nature today1 by Xing Xu, a palaeontologist at the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, and his colleagues. It was found in western Liaoning, China, in rocks dating to the Late Jurassic epoch, 161 million–145 million years ago. Like many similar fossils, it is surrounded by feather impressions in the rock, but has claws on the ends of its forelimbs and sharp teeth.

    These traits by themselves do little to help place the fossil in the dinosaur–bird transition, but Xu reports that it also has extremely long middle and last finger bones and a wishbone with an L-shaped cross-section at one end. These characteristics, Xu argues, identify Xiaotingia as very closely related to Archaeopteryx and another feathery relative, Anchiornis.

    After analysing the traits present in Xiaotingia and its relations, Xu and his colleagues are suggesting that the creatures bear more resemblance to the dinosaurs Velociraptor and Microraptor than to early birds, and so belong in the dinosaur group Deinonychosauria rather than in the bird group, Avialae. Many features led the team to this decision, but the most immediately noticeable are that Xiaotingia, Archaeopteryx and Anchiornis have shallow snouts and expanded regions behind their eye sockets. Microraptor has similar traits, but the early birds in Avialae have very different skulls.
    However, the article (written in 2011) also warns that we should not be quick to make snap judgments about these sorts of discoveries:

    Whether this change will be permanent depends on what other animals are discovered in the future, says Thomas Holtz, a palaeontologist at the University of Maryland in College Park. "I don't think this is going to be the last word on this subject. You take this new Chinese species out of the mix and the argument falls apart, so the new placement is precarious at best until further evidence is dug up."
    It's very interesting, don't get me wrong, but the issue is far from settled. Hence, my original claim that there is "spirited debate" amongst the community regarding the origins of Avialae.
    Last edited by Static_Martyr; 01-11-2013 at 04:48 PM.
    "I'm sorry
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    For all the people I never stopped
    But there was nothing I could do...
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