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To answer your first question: no, the different
pelvis bones as well as the differences in the vertebral columns demonstrate
that "dinosaurs", to judge from their weak backbones, originated from aquatic
saurischian forms, as well as Archaeopteryx (and Compsognathus),
but obviously all ornithischians became basically terrestrial.
question 2: It is rather probable that bats also
evolved underwater, but the fossil record so far is too thin for such a
statement. There is no possibility else.
Sorry, I meant to say Eoalulavis.
Sorry, but I cannot safely identify any
(terrestrial) cursorial or gliding adaptations in maniraptorians (if they really
were).
Be skeptical, that is your good right. But you
should not believe, belief is not a matter of natural
sciences.
Klaus
----- Original Message -----
Sent: Thursday, April 14, 2005 4:52
PM
Subject: Re: paleonet Origin of
flight
Don't you also believe that ALL dinosaurs were aquatic...?
> An evolution is never accidental, and it is an old and erroneous
myth that flight is either
> possible from ground to air or from trees to ground, unfortunatety
completely ridiculous.
So bats also evolved underwater??
> There is a direct evolutionary line from unidentified aquatic
precursors via long-tailed
> rhamphorhynchoids to pterodactyloids, as well as in another line to
birds via Archaeopteryx
> and Alulavis hoyasi.
Excuse the nit-picking, but I think you mean _Eoalulavis hoyasi_.
This is an understatement, but I'm very skeptical about bird flight (or
pterosaur flight) evolving in the aquatic medium. Very skeptical
indeed. The presence of both cursorial and gliding adaptations in some
maniraptorans has made the "ground-up" and "trees-down" hypotheses for the
origin of avian flight not just possible but compelling. Personally I
believe that both gliding and running were important in the evolution of the
flight stroke, and that these pre-avian maniraptorans could both run on the
ground and climb trees.
Cheers
Tim
Klaus Ebel <klaus@ebel-k.de> wrote:
Dear paleonetters,
sorry that I must make this statement, however,
fossil hunters and paleontologists are very restricted concerning their
abilities to determine the origin of flight. They only can derive
their tales (sensu Steven J. Gould) from fossil remainders, but they
cannot see the problems restricting an evolutionary path or making it
entirely impossible. An evolution is never accidental, and it is an old and
erroneous myth that flight is either possible from ground to air or from
trees to ground, unfortunatety completely ridiculous. Fossil remainders per
se cannot reveal unequivocally evolutionary lines, though of
course they are not in contrast to the truth. Physical conditions
clearly dominate any evolution and must be taken into account to arrive at
reliable results. As a experienced expert in aerodynamics and flight
mechanics I have done so (www.ebel-k.de). There is a direct
evolutionary line from unidentified aquatic precursors via long-tailed
rhamphorhynchoids to pterodactyloids, as well as in another line to birds
via Archaeopteryx and Alulavis hoyasi.
Klaus
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