Researchers reporting in the journal Science describe a study of alligator lungs that showed an air-circulation mechanism similar to birds’. A team led by evolutionary biologist C. G. Farmer of the University of Utah made the discovery by pumping fluids through dead alligators’ lungs to determine the direction of airflow.
Even if the bird–alligator lung similarity is unique, it need not show that the two share a common ancestor.
As in birds, the fluid flow in alligators shows that air bypasses certain airways initially, later flowing through them before being exhaled. This high-efficiency, one-directional mechanism keeps birds’ lungs consistently filled with “fresh” air, enabling them to breathe at high altitudes.
Because most evolutionists believe birds evolved from dinosaurs—and that alligators and dinosaurs shared a common ancestor—the team believes this breathing mechanism first evolved in the common ancestor around 200 million years ago or more.
But assuming the researchers’ method accurately captures the workings of the alligator lung, the similarity to the bird lung may be less meaningful than Farmer’s team implies—as is suggested in a ScienceNOW discussion of the thoughts of University of Washington morphologist Adam Summers:
“We don’t know how other critters breathe—lizards, for example.” It could be that unidirectional airflow is the pattern for all nonmammalian land vertebrates, [Summers] says. That would make mammals, rather than birds, unique in the way they breathe. “It reopens a lot of questions that we thought were closed,” he says.
Even if the bird–alligator lung similarity is unique, it need not show that the two share a common ancestor; they could just as easily have a common designer. And indeed, not all evolutionists are convinced that birds evolved from dinosaurs, as shown by a study we covered last June.
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