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re: Coelurosauravus: glider? or bluffer?



David Peters (davidrpeters@earthlink.net) wrote:

<dp: I'm thinking of pterosaurs in the size range of the gliding lizards.
Probably no bigger than a man's hands. And if the wing tips are the
problem, perhaps we could hold one at mid digit for the same analogy.>

  The tensile strength of a bone increases with size, and inversely the
bending moment increases with a decrease in size; couple this with the
fact that mass decreases with size (duh) and you get an animal that is
relatively stronger for its mass than an elephant, and the bone strength
will be a LOT more pliable and resistant to stresses affecting larger
bone. You CAN pick *Draco* up by it's "wings" and I've seen people do
this, without apparent injury to the lizards.
 
<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? One is essentially erasing research and drawing ones own lines of
development without any constraint, or similar developmental research, to
support one's conclusions (like "special" ontogeny in pterosaurs).

  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.*

<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.

<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.*

<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.

  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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