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Re: Coelurosauravus: glider? or bluffer?




"Jaime A. Headden" wrote:

>
> <dp: yes, but you're going back to fish here.  In Coelurosauravus it's
> like going back to dermal ossicles, like Stegosaurus or horned toad
> spikes. Scales gone crazy.>
>
>   Not really, but possible. First off, I can only recall in one reall
> interesting development of a "scale" forming an articulated joint with an
> adjacant bone, and that's the titanosaur *Augustinia.* However, why must
> one question developmental biology and ontogeny to make one's theories
> correct?

I'm not questioning dev. bio., but the development of the skull in fish versus 
skin ossicles in reptiles leads me to believe that you are arguing for 
argument's sake, and for that credibility is in danger of being lost.

>
>   Second off, I note a very interesting similarity to *Longisquama* in
> that the dorsal structures of *L.* parallel curvature in *C.,* as well as
> placement (on top of the skeletal characters that Senter noted, which I
> forgot to ask him about at SVP this year), so it is easy to see the one
> develop from the other, so either *L.* "lost" the dermal bone (failure to
> ossify during ontogeny) or *C.* ossified them from unossified
> cartilagenous cores that were likely present in the "rachis" of *L.* that
> Jones et al. use to "prove" these were feathers. No matter. It offers a
> possible secondary development of a patagium versus slatted patagiata in
> the "wing" structure, as in *L.*

Uh, oh, we're mixing up single row dorsal (Longisquama) and lateral 
(Coelurosauravus) structures here. You wanna reconsider your statement?

>
>
> <please stay on the same merry-go-round. Anything diapsid
> andPermo-Triassic would be better. And  all other arboreal diapsids did
> not adopt this pattern.>
>
>   Dave asked for other animals with a similar pattern, and the pattern was
> offered. For an example, *Kuehneosaurus* is so near to the amniote base
> and origin of reptiles in some trees that it might as well be ridiculous
> to NOT consider the possibility of other amniotes than diapsids here.

Bringing human anatomy into Permian diapsid discussions is inappropriate in 
most instances.

>
>
> <regarding the anterior process of the ilium and bipedalism: It only takes
> a  tiny nubbin of an anterior process in extant lizards to put them in the
> bipedal camp. Which makes it easier, if you like analogies, to attribute
> bipedalism to species we will never meet. If analogies don't work for you,
> then lots of arguments go belly up.>
>
>   Have you, Dave, considered the biomechanical properties of this "nubbin"
> and it's actual use in bipedal versus quadrupedal animals? It is obvious
> from various other animals with slightly elongated regions of the ilium
> anterior to the articulating sacrals that there is not a very strong
> bipedal component, including in both apes and *Megalancosaurus.*

Snyder 1954 did the work and it makes sense because it can be tested. Snyder's 
work and my references pertain to lizardy diapsids only, as I've said before. 
Besides apes and drepanosaurids are/may have been capable of their very own
special forms of bipedalism, in the latter case much like a chamaeleon, in both 
cases by grasping a branch with the hind feet alone. And Jaime, you knew that 
writing that objection.

>
>
> <Again, as in bats and birds, the fore limbs/fins of flying fish are
> chained to internal bones and muscles, unlike the skin of
> Coelurosauravus.>
>
>   The rods of *Coelurosauravus* are also "chained" to internal bones (ribs
> and as noted, also the pectoral girdle), and like the cranial feathers and
> retrices, entombed in nothing but muscle and skin and would likely have
> worked just as beautifully.

Skin alone in the case of Coelurosauravus, and the shiver muscles in the 
dermis, nothing deeper. Nothing connected to the skeleton proper or its muscles 
- other than a butt joint (the weakest of all in carpentry) on the very tip of 
the rib
with dermal fascia separating it.

I'm through with this thread.

dp

>
>
>   Cheers,
>
> =====
> Jaime A. Headden
>
>   Little steps are often the hardest to take.  We are too used to making 
> leaps in the face of adversity, that a simple skip is so hard to do.  We 
> should all learn to walk soft, walk small, see the world around us rather 
> than zoom by it.
>
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
>
>
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