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Thread: Pterosaurs as the first time dinosaurs evolved flight

  1. #1 Pterosaurs as the first time dinosaurs evolved flight 
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    Information from Robert Bakker's Dinosaur Heresies (not direct quote):

    Pterosaurs share some unique anatomical features that MAKES them dinosaurs as well! It was indeed derived from their Archosaur ANCESTORS - but Pterosaurs, although close to the base, were NOT archosaurs - they diverged early, but they diverged from an early DINOSAUR ancestor!

    unique features identical to dinosaurs:

    1) S curve neck - dinosaurian, not archosaurian
    2) Air sacs within hollow bones - only the dinosaurs have this feature; both the extinct land ones and the modern avian ones. - dinosaurian, not archosaurian
    3) anterior jaw muscle fenestrae - dinosaurian, not archosaurian.
    4) Support strut on lower jaw joint - dinosaurian, not archosaurian.
    5) Pterosaurs without clavicles also - dinosaurian, not archosaurian.
    6) Pterosaurs with hinge-only ankle - - dinosaurian, not archosaurian.(Archosaurian having bent hinge line - ability to stand on blade of foot)
    7) DEFINITELY warm blooded, the same as dinosaurs; although archosaurs may have been, too - I don't know about their haversion canals or growth rings; they may have been primitively warmish-blooded, like protomammals.

    Reference: chapter 13 of "The Dinosaur Heresies" ISBN 0-8217-2859-8
    Also check the work of Jose Bonaparte who also identifies Lagosuchus - a DINOSAUR and not an archosaur, as the ancestor of Pterosaurs.


    This is condensed from another website where I posted.
    The maturity level there is far below this one.
    Are there Paleontologists here with experience in this field of inquiry?


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  3. #2  
    Time Lord Paleoichneum's Avatar
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    IF it were that simple then I would have expected Bakker to have published in a P.Rev. journal moving them into Dinosaurimorpha and synonymizing Pterosaurimorpha.

    However the issues are rather more complex then Bakker shows. A 2008 paper(1) describing an aborial pterosaur from China asserts that the ancestor of group was an insectivorous tree dweller. While many more accepted hypotheses have Sharovipteryx or a close relative as the origin point for the pterosaurs.

    My thoughts...

    At this point there simply isn't enough data to state for certain where the pterosaurs belong to make any sort set in stone statements.


    (1)Discovery of a rare arboreal forest-dwelling flying reptile (Pterosauria, Pterodactyloidea) from China


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    WYSIWYG Moderator marnixR's Avatar
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    your definition of archosaur seems to be different from what i understand the word to mean - i thought archosaur meant the groups encompassing dinosaurs, pterosaurs and a variety of what used to be called thecodonts

    hence, a dinosaur IS an archosaur
    what you're referring are the characteristics that make dinosaurs a derived subset of archosaurs
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  5. #4  
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    I'm not aware of what Bakker published in journals beyond his reference section for "Dinosaur Heresies".


    Thanx for the clarification marnixR.
    It seems though, that there ought to be a reclassification/renaming if you have a group - or groups - that developed homeothermy and a high metabolism out of a group that didn't? Or else maybe I need to replace "Archosaur" with some other non-dinosaurian ancestor name at a lower level of grouping.
    I haven't cracked open my textbooks in some time - it's too bad I gave away my lab manual also - it had a very detailed classification table on a poster.

    Do you have any classification tables that have the current picture at a glance?

    In any event; that was my intent - to repeat the case that pterosaurs evolved from dinosaurs, and are not a sister-group evolving alongside them; close but nevertheless separate.
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    WYSIWYG Moderator marnixR's Avatar
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    happened to find a piece of old-style forum post entitled "dinosaur synapomorphies?"

    the bits between < ... > appear to be quotes, with the replies inbetween those

    the poster appears to try and refute a claim of "pterosaurs are dinosaurs" by comparing the pterosaur condition for against each of the 17 synapomorphies identified by Sereno, and claiming that they fail on all of them
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    Now that's something worth reading.

    I feel that we can't really judge the subject matter without photographs.

    shallow and marginal expression of the trochanters
    I need to see examples of the bones he's talking about to fully understand his statements beyond the dry writing. Some specialists apparently disagree with this writer. Presumably they would do so on strong grounds of evidence.

    We need time periods for the fossils he's talking about as well as collection locations. Depositional environments might even help give a clue to the life environments of the animals he's talking about - though pretty troublesome to tie down for flying animals.

    It's not like I'm superbly interested in the flying dragons - I'm alot more interested in the proof of T-Rex as a hunter rather than scavenger. I just thought there would be alot more concise and well researched papers on the matter.

    Though I do agree there is simply not enough fossil evidence accrued yet to be sure.
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    WYSIWYG Moderator marnixR's Avatar
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    sorry, i'll have to default here - i don't have access to any illustrations that might enlighten you (or myself, for that matter)

    is there anyone out there who can put their hands on some pix or drawings for the sake of clarification ?
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    Yes, I don't trust my plastic models to be absolutely accurate...

    (shameless showoff):

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    Forum Professor sunshinewarrior's Avatar
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    Quote Originally Posted by C_Sensei
    It seems though, that there ought to be a reclassification/renaming if you have a group - or groups - that developed homeothermy and a high metabolism out of a group that didn't?
    Would violate the rules of cladistics and therefore run counter to all modern systematics.

    Which is why (counter-intuitively) a dolphin is actually a fish, and apes are really monkeys and so on (despite what we taught in school).
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    Science is self-correcting. We can correct the system if it's needed.
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