June 9, 2009 — “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.” That statement is not being made by creationists, but by science reporters describing work at Oregon State University that cast new doubt on the idea that birds evolved from theropod dinosaurs. The main idea: their leg bones and lungs are too different.
Science Daily’s report has a diagram of the skeleton showing how the fixed femur is tied into the avian lung system. Birds use more oxygen than mammals.
Their flow-through lungs would collapse if the femur moved like it does in mammals, reptiles and dinosaurs. “It’s really strange that no one realized this before,” said Devon Quick, professor of zoology at OSU, speaking of the tie-in of the femur to the bird lung. “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.”
His colleague John Ruben was equally surprised: “It’s really kind of amazing that after centuries of studying birds and flight we still didn’t understand a basic aspect of bird biology.” The article began, “The conclusions add to other evolving evidence that may finally force many paleontologists to reconsider their long-held belief that modern birds are the direct descendants of ancient, meat-eating dinosaurs.” Key paragraphs put this in context:
“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.
“A velociraptor did not just sprout feathers at some point and fly off into the sunset,” Ruben said.
For a claim dinosaurs had air sacs, see the 09/29/2008 entry. The OSU professors are not disbelieving in evolution. Birds and dinosaurs may have had a more distant common ancestor, they said: “It just seems pretty clear now that birds were evolving all along on their own and did not descend directly from the theropod dinosaurs, which lived many millions of years later.”
Oregon State has been at the forefront of challenging the dogma: “OSU research on avian biology and physiology was among the first in the nation to begin calling into question the dinosaur-bird link since the 1990s.” Doubts have also been raised at other institutions. Why has the story persisted? For one, “old theories die hard, Ruben said, especially when it comes to some of the most distinctive and romanticized animal species in world history.” Another reason is museum politics:
“Frankly, there’s a lot of museum politics involved in this, a lot of careers committed to a particular point of view even if new scientific evidence raises questions,” Ruben said. In some museum displays, he said, the birds-descended-from-dinosaurs evolutionary theory has been portrayed as a largely accepted fact, with an asterisk pointing out in small type that “some scientists disagree.”
“Our work at OSU used to be pretty much the only asterisk they were talking about,” Ruben said. “But now there are more asterisks all the time. That’s part of the process of science.”
That being the case, we can expect heated comeback arguments from those committed to the dominant view. Nevertheless, they will have to contend with the problem of evolving a fixed femur from dinosaurs who had a moving one – and in a shorter time than the fossil evidence allows.
The new work was published in the Journal of Morphology and was funded by the National Science Foundation, the article said. This story was also reported by PhysOrg and E! Science News. Time will tell if the other major science reporters pick it up. As of June 10, they did not, but Astrobiology Magazine did.
Sometimes the key to a story is in the asterisks. The OSU professors should be commended for going against a strong current of dogma in their field. Notice how many non-evidential factors producing that dogma were pointed out in the article: careers on the line, museum politics, romanticized notions, and old die-hard theories presented as fact. Those are the same non-evidential factors running rampant throughout King Charles’ domain. He’s the one that needs to go flying off into the sunset – with velocity.
The OSU profs saved their skin, though, by still pinching their incense to Caesar, claiming that the mythical “common ancestor” is just a little further back in the record, and that birds were “evolving in parallel” along with the dinosaurs. That’s all they can do – toss in a few more naturalistic, purposeless, chance miracles to keep the Bearded Buddha shrine operating. Now the museum workers are going to have to figure out what to do with all those feathers (01/21/2009, 07/09/2008, 06/13/2007, 02/08/2006). Maybe they can stick them on the wooly mammoths, as caricatured by Tom Weller in Science Made Stupid, a mandatory lesson on how evolutionary stories are propagated.
0 comentários:
Post a Comment
Be respectful. Comments are moderated.