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DomKen -> RE: Birds Of Prey (4/12/2010 9:32:04 PM)
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some caveats about these press releases
quote:
ORIGINAL: Kirata
~ FR ~
I didn't want to hijack the thread with this, so I sent it to Thomas privately. But he said to go ahead and add it, as it might open an interesting discussion. So for anyone interested, the bird-dinosaur link, mentioned in the OP, is actually starting to look a little thin...
ScienceDaily (June 9, 2009) — Researchers at Oregon State University have made a fundamental new discovery about how birds breathe and have a lung capacity that allows for flight – and the finding means it's unlikely that birds descended from any known theropod dinosaurs.
The issue is with the mobility of the femur. All modern birds have immobile femurs and it is involved in their lung action. However no other animals with femurs had this feature including some types of extinct birds. To therefore claim that birds could not be descended from animals with mobile femurs is impossible. To discount the therepods as ancestors of Aves on this basis is completely untenable until a non bird with immobile femurs like modern birds is found which considering that some extinct birds had mobil femurs seems very unlikely.
quote:
ScienceDaily (Feb. 10, 2010) — A new study just published in the Proceedings of the National Academy of Sciences provides yet more evidence that birds did not descend from ground-dwelling theropod dinosaurs, experts say, and continues to challenge decades of accepted theories about the evolution of flight.
K.
This one is also hyped up quite a bit. The issue isn't whether Aves is descended from Dinsuria but whether flight developed from the ground up or from the trees down. We have evidence for both but recent finds are leaning towards the trees down model. As to some dinosaurs possibly being secondarily flightless, it is entirely possible but no compelling evidence exists for such a stand.
A good book on subject, predates the most recent finds, is Dinosaurs of the Air by Paul.
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