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Re: Protoavis



  Sorry about the name mix-up.

Larry Febo wrote:

<Pterosaurs did have (what is termed by Padian at least) an
acrocoracoid process. They may have lacked the furcula as part of the
structure, but it`s there nonetheless, and functions pretty much
exactly as it does for a bird.>

  An acrocoracoid process, pulling the _M. biceps_ muscle (being
redundant for simplicity) would fling the humerus sideways---it does
in us (the muscle, that is) and in large terrestrial reptiles (crocs
and monitors) you see the huge sideways lunge of the body with a
sideways fling of the arm on the opposite side of the lunging
direction. This is supported by the acrocoracoid, and suggests that
the structure would have developed---originally---for just such a
purpose to a extreme method in particular groups. When the
ornithodiran line became bipedal, starting somewhere around
*Lagerpeton* or so (with long forearms but with big feet) the
acrocoracoid was preempted. Now, if pterosaurs were related closely to
dinosaurs (= Ornithodira) there would have been a common, terrestrial
origin (and possible bipedal one) for both lineages (provable, I
guess, if *Scleromochlus* was a pterosaur ansestor) then development
of the acrocoracoid into a flight structure among birds and pterosaurs
in convergent. I don't argue for this, or for yours, Larry. I actually
like the elegance of your theory.

  However, the lagosuchid -> herrerasaurid -> dinosaurian ->
theropodan -> maniraptoran -> bird relationship argues against such
association. Alternatively, a common ansector for pterosaurs and birds
as full flight development so early on leaves most of these dino-birds
in the dust. Were dinosaurs trying to redevelop birds? These animals
were getting bigger, not smaller, or more terrestrial. Looks like
they'd taken a hop _down_, not trying to claw their way back _up_.
BCF, if I'm not mistaken, but George and others have argues this all
before.

  The point I'm trying to make is that is birds _had_ developed early
on, one would think that all theropods wouldn't retain, loose, and
regain all these "bird" characters. Rather than having a common origin
for all flight features that, orignally, had nothing to with flight.
Arboreality? Scansoriality? You be the judge.

  And about Protoavis: the hand possesses all fight metacarpals, with
several having the appearance of being warped and distorted. And there
is a photo of the specimens in a relatively accessible resource:
Feduccia's _Origin and Evolution of Birds_. It's an itty-bitty
picture, but there _is_ one.

<As far as bats flying as "good" as birds,...it`s pretty subjective,
but I don`t think they`re as good long range, and I`m assuming that
hummingbirds might be able to outmaneuver them...(though not at
night!).>

  Bats do fly for long periods, hours on end, and eat on the wing,
being fully capable of "netting" prey by the wings and eating while
flying. For hours on end. The size of hummingbirds gives them much of
their maneuverability, having so little mass to have to resist (hence
the teeny wings) that the point is pretty moot, IMO.

<Archie flew , I think,..(although some say not very
efficiently),...it did not have an acrocoracoid process,...did have a
biceps tubercle though.>

  Demonstrating, in the least, that the ac. pr. is a flight related
feature, not a flight requisite one, but bats should also point that
out.

==
- Often, it is the man who is brought
  down the path to the end who does
  not see his own steps. -

Jaime A. Headden

Qilong, the website, at:
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