Birds not closely related to dinosaurs

[JohnGW]

As usual, I've been waiting for Stonjek to put this up, but he
hasn't. I would be interested in any comment on this:

http://www.sciencedaily.com/releases/2009/06/090609092055.htm

John GW

[Darwin123]

On Jun 16, 8:19=A0pm, JohnGW <jgi...@abcinet.net> wrote:
> =A0 =A0 =A0 As usual, I've been waiting for Stonjek to put this up, but h=
e
> hasn't. =A0I would be interested in any comment on this:
>
> http://www.sciencedaily.com/releases/2009/06/090609092055.htm
>
> =A0 =A0 =A0 John GW
The controversy is whether the birds split off directly from
theropods in the middle of the Mesozoic, or from thecodonts somewhat
earlier. This controversy keeps on resurfacing. The article claims to
the movable femur of theropods, which birds don't have, as evidence
that the birds could not be directly descended from theropods.
While this is certainly interesting evidence, I don't think the
movable femur eliminates the possibility that birds were descended
from theropods. The immobilization of the femur could of occurred
later in the evolution of birds, when they were evolving flight.
Some theropods seem to have hollow bones and an expansion of lung
capacity that suggests they were developing the better developed lung
while they were on the ground. The improved lung would have helped
them run faster and longer. The theropod ancestral to birds did not
have to have the fully developed lung-skeleton system that birds used.
There are other points that the article did not clarify. We don't
know if any known thecodonts had immobile femurs. We don't know if any
of the early bird fossils had immobile femurs. The Archeopteryx
skeleton, for instance. Does anyone know how "immobile" the femur in
Archeopteryx was?
However, the authors may be right. I think birds could have split
off from thecodonts in the Triassic or upper Permian. Maybe the lung
structure, feathers and so forth developed in parallel. I think a
study of the femurs in both Mesozoic birds and thecodonts could help
resolve this issue.

This is a quote.
"There are some similarities between birds and dinosaurs, and it is
possible, they said, that birds and dinosaurs may have shared a common
ancestor, such as the small, reptilian "thecodonts," which may then
have evolved on separate evolutionary paths into birds, crocodiles and
dinosaurs. The lung structure and physiology of crocodiles, in fact,
is much more similar to dinosaurs than it is to birds."