Origin of Birds

The existence of waterfowl had not escaped my notice. I didn't mean to suggest that loons and ducks and other fowl don't "swim", per se, but that they certainly don't swim in the manner of penguins, who have feathers, lungs and (especially) wings evolved for lengthy underwater locomotion. These same adaptations rob them of flight.I guess it's kind of splitting hairs, but ducks and other waterfowl don't "fly" underwater to nearly the same degree that penguins do. But I guess it's just a difference of degree. In the same way that splashing in the kiddee pool and swimming the English channel is a difference of degree. Penguins don't fly, right? We can agree on that?(As for Prior Lake, the loons do avoid it - it's a pretty suburban area. All the jet-skis and powerboats scare them off. Not good fishing, either. Which is too bad, I do love those loons, I just don't think of them as particularly excellent swimmers. ------------------
Epimenedes Signature: This is not a signature.

Andya,

quote:

---

Of course the dino-bird hypothesis will need to account for the absence of more ancestral forms in pre-Archaeopteryx times.

---

Not really, like you say, we need more fosils. In a cladogram, supported by a poor fossil preservation it is possible for stratigraphy & cladistics to mismatch 100%. Not an ideal situation, I agree, but it is reality. Ancestral morphologies may post-date the more derived ones as we see them now in the fossil record due to stasis. The fact remains (at the moment!) that the therapod (dinosaur) - bird hypothesis is supported by many synapomorphies, & basal archosaur - bird hypothesis, by none.Mark------------------
Occam's razor is not for shaving with.[This message has been edited by mark24, 04-09-2003]

But auks and shearwaters do swim underwater using their wings, and do fly too.Check out this site:..
http://www.stanfordalumni.org/...e/text/essays/Swimming.htmlThe Common Murre is particulary adept at flying in air and underwater. http://personal.southern.edu/...hurch/website1/chapter4.html It's an awesome bird!

Wow, do they? Then I sit corrected.Clearly I do not know from birds. I appreciate the info. I wouldn't have believed it, but there it is.I confess I may have been arguing from a kind of design: "It's impossible to design wings that work both underwater and in the air, therefore, no such wings could exist." One more instance of how random variation + natural selection produces results superior to design.Thanks for the heads-up.------------------
Epimenedes Signature: This is not a signature.

Not sure how relevent it is, but there is an article
in Scientific American, march 2003 about the evolution
of feathers that mentions a host of fossil remains
from china that appear to show the development of feathers in
a manner consistent with developmental studies of modern
bird feathers.

Please elaborate, which fossils are they? I have no problem with raptors having feathers. My hypothesis would be that raptors evolved from ancient birds.Btw I finally got my hands on that Chatterjee paper (it was a nasty 14MB pdf from JSTOR). As some of you might already know, his Protoavis are widely misused by creationists as an example of 'perfect bird--proof of creation'. And having seen the fossil bones, I laughed. Protoavis looks just like Archaeopteryx!! Teeth, fingered wings, long tail... can't mistake it for modern birds!

I don't have the issue to hand at the moment (it's in
the library at work) so i'll have to post the details
when I'm next in the office.Basically it suggests that feathers evolved gradually,
and in line with the way that modern feathers grow in
developing birds. There are references to some fossils
which seem to show simple out-growths, then more recent
fossils where these are slightly more complex, etc.Like I say, I'll need to grab the copy to give proper details.

Im just wondering. How many times has flight had to evolve? There's insects, birds, pterosaurs, bats. I have even heard that since there are 2 very differnt types of bats, that they must have evolved separately.

Sinosauropteryx -- tubular structures.
Sinornithosaurus -- open tufted structures lacking a rachis.
Alvarezsuarids -- Planar feather with unbranched barbs fused to central rachis.
Oviraptorosaurus,Troondontids -- Closed pennaceous vane.
Archaeopteryx,Confuciusornis, Enantiornithes -- Closed assymetrical vane similar to modern flight feathers.The article is in Scientific American March 2003 by Richard O.Prum
and Alan H. Bush.They are suggesting that feathers evolved in dinosaurs, and that
effectively birds are one group of therapod dinosaur that
developed powered flight.They also suggest that dinos. such as T.Rex may have been feathered.

It certainly seems that several different species developed
the structures necessary for powered flight, and at different
times.Do you see a problem with that suggestion or were you just
wondering?