Why birds could not have evolved from theropods

[Spud]

Research at Oregon State University showed that birds are not dinosaurs, neither did they evolve from them. They think that birds and dinosaurs may have evolved from a common ancestor.

It's been known for decades that the femur, or thigh bone in birds is largely fixed and makes birds into "knee runners," unlike virtually all other land animals, the OSU experts say. What was just discovered, however, is that it's this fixed position of bird bones and musculature that keeps their air-sac lung from collapsing when the bird inhales.

Warm-blooded birds need about 20 times more oxygen than cold-blooded reptiles, and have evolved a unique lung structure that allows for a high rate of gas exchange and high activity level. Their unusual thigh complex is what helps support the lung and prevent its collapse.

"This is fundamental to bird physiology," said Devon Quick, an OSU instructor of zoology who completed this work as part of her doctoral studies. "It's really strange that no one realized this before. The position of the thigh bone and muscles in birds is critical to their lung function, which in turn is what gives them enough lung capacity for flight."

However, every other animal that has walked on land, the scientists said, has a moveable thigh bone that is involved in their motion – including humans, elephants, dogs, lizards and – in the ancient past – dinosaurs.

The implication, the researchers said, is that birds almost certainly did not descend from theropod dinosaurs, such as tyrannosaurus or allosaurus. The findings add to a growing body of evidence in the past two decades that challenge some of the most widely-held beliefs about animal evolution.

"For one thing, birds are found earlier in the fossil record than the dinosaurs they are supposed to have descended from," Ruben said. "That's a pretty serious problem, and there are other inconsistencies with the bird-from-dinosaur theories.

"But one of the primary reasons many scientists kept pointing to birds as having descended from dinosaurs was similarities in their lungs," Ruben said. "However, theropod dinosaurs had a moving femur and therefore could not have had a lung that worked like that in birds. Their abdominal air sac, if they had one, would have collapsed. That undercuts a critical piece of supporting evidence for the dinosaur-bird link.

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

[Sebastian Toe]

enki said,

http://www.religionethics.co.uk/index.php?topic=12171.msg624490#msg624490

Research at Oregon State University showed that birds are not dinosaurs, neither did they evolve from them. They think that birds and dinosaurs may have evolved from a common ancestor.

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

...and that relates how exactly,  with the statement;
 "As far as I know there is no scientific non evolutionary reason for bird flight."
??

[Spud]

Hi Seb,
I suppose it doesn't relate to the statement... it was careless of me to quote that, and I think it might be best to delete it from the OP, which I've just done. I had tried to find out a bit about how flight in birds is thought to have evolved, and I came across the article in the process. I thought it was quite interesting.

[SteveH]

One single solitary piece of research or published paper doesn't necessarily overturn the received wisdom at a stroke. 

[L.A.]

Research at Oregon State University showed that birds are not dinosaurs, neither did they evolve from them. They think that birds and dinosaurs may have evolved from a common ancestor.

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

You might find this a bit more informative Spud:

http://www.rvc.ac.uk/Media/Default/Structure%20and%20Motion/Documents/23.pdf

[Spud]

You might find this a bit more informative Spud:

http://www.rvc.ac.uk/Media/Default/Structure%20and%20Motion/Documents/23.pdf

Thanks. I think the Oregon university paper was written after at the same time as that one. Will be interesting to compare them.