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Re: FW: The birds vs. the pterosaurs



Edwards Clark D SSgt 51 MDG/SGPF (clark.edwards@osan.af.mil)
wrote:

<It may also be noted that pterosaurs were, after all, reptiles.
 Not really having the ability to survive climatic changes as
well as an animal with even rudimentary fur or, in this case
feathers, would put a fundamentally severe strain on their
ability to compete with a smaller, faster, perhaps much more
maneuverable creature.>

  I'd hate to say this to a member of the military, but to use a
Bakkerism, this is "bunk." No one can establish the absolute
parameters of pterosaur, early bird, or early bat biology or
metabolism to say to which degree one organism has the ability
to over-establish itself as "survivable" or not. Reptiles are
not prone to extinction, mind you, for such are birds, crocs,
turtles, etc, who all survived the K/T and Eocene extinctions,
the last two of which also the "big" P/T extinctions, so these
are _survivors_. To say that a pterosaur, being either reptilian
or ill-equipped with integument (non-fur, non-feathers) or are
less-maneuverable (pterosaurs possess a structure of the wing
(pteroid) that functioned in the mein of an alula, along with
birds with alulae, and as of the Triassic, well before such.
Pterosaur flight dynamics are by the far as complex as bird
flight dynamics were in the Mesozoic, if not better, and only in
modern avian lineages (Carinatae, as of the Cenomanian of the
Late Cretaceous, given *Apsaravis*) were the truly special
flight mechanics developed, especially the main pectoral
mechanics and body form.

  Bats arrived by the [earliest record, I recall] early Eocene
but may have been lastest Cretaceous or early Paleocene given
the specialization already present in these forms, so were
hardly in competion as we know with _any_ pterosaurs, as the
lastest known surviving pterosaurs are [in the Campanian]
azhdarchids and pteranodontids and [in the Maastrichtian]
azhdarchids. These pterosaurs were whole class-sizes above most
projectable bird size and certainly any bat size. Similarly,
outcompeting a pterosaurs in the Early Cretaceous must also
regard nich partitioning: in levels containing pterosaurs and
birds, what niches have been proposed for the birds _and_ the
pterosaurs, and which sizes are these in relation to one
another? Some places to look: the Niobrara Chalk (mid-Plains
States, USA), Campanian, and the Bissekty (Uzbekistan),
Turonian; Las Hoyas, the Morrison, and the Solnhofen are avid
producers, but true values of both forms are hardly satisfying:
the first has birds aplenty, but I don't know of any pterosaur
strata; the second has _some_ pterosaur, but I know of no birds;
and the third has pterosaurs in profusion (*Rhamphorhynchus,*
*Pterodactylus,* *Gnathosaurus* -- I could go on...) but no
apparent avian remains aside from *Archaeopteryx,* and this a
relatively primitive form lacking most of the "true" avian
equippage to be of a challenge to pterosaurs except maybe
metabolic.

  And on that note I shall end this post: Greg Paul has done a
wonderful painting of a pteradactylid confronted by two
aggressive-looking Archies -- what might we read in this?

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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