[myself00]

The avian lung

Drastic changes are needed to turn a reptile lung into a bird lung. In mammalian lungs, the air is drawn into tiny sacs (alveoli, singular alveolus) where blood extracts the oxygen and releases carbon dioxide. The stale air is then breathed out the same way it came in. Reptiles have the same bellows system, but their lungs are septate; i.e. like one big alveolus divided by centrally directed ingrowths called septa (singular septum) coming from the walls. The gas exchange occurs mostly on the septa. Birds also have septate lungs, but their breathing is much more complex. But birds, in addition to their lungs, have a complicated system of air sacs in their bodies, even involving the hollow bones. This system keeps air flowing in one direction through special tubes (parabronchi,singular parabronchus) in the lung, and blood moves through the lung's blood vessels in the opposite direction for efficient oxygen uptake,25 an excellent engineering design.26
How would the ‘bellows’-style lungs of reptiles evolve gradually into avian lungs? The hypothetical intermediate stages could not conceivably function properly, meaning the poor animal would be unable to breathe. So natural selection would work to preserve the existing arrangement, by eliminating any misfit intermediates.
Also, even assuming that we could construct a theoretical series of functional intermediate stages, would natural selection ‘drive’ the changes? Probably not—bats manage perfectly well with bellows-style lungs—some can even hunt at an altitude of over two miles (three km). The avian lung, with its super-efficiency, becomes especially advantageous only at very high altitudes with low oxygen levels. There would thus have been no selective advantage in replacing the reptilian lung.27
We should probably not be surprised that Alan Feduccia's major work on bird evolution doesn't even touch this problem.28
Some recent researchers of Sinosauropteryx's lung structure showed that ‘its bellows-like lungs could not have evolved into high performance lungs of modern birds.’29
Interestingly, some defenders of dinosaur-to-bird evolution discount this evidence against their theory by saying, ‘The proponents of this argument offer no animal whose lungs could have given rise to those in birds, which are extremely complex and are unlike the lungs of any living animal.’30 Of course, only evolutionary faith requires that bird lungs arose from lungs of another animal.
References and notes

1. Cited in V. Morell, Archaeopteryx: Early Bird Catches a Can of Worms, Science 259(5096):764–65, 5 February 1993.
   
2. Courtesy of Steve Cardno, 1994.
   
3. A. Feduccia, Evidence from Claw Geometry Indicating Arboreal Habits of Archaeopteryx, Science 259(5096):790–793, 5 February 1993.
   
4. D. Menton and C. Wieland, Bird Evolution Flies Out the Window, Creation 16(4):16–19, September–November 1994.
   
5. The Examiner, Launceston, Tasmania, 19 October 1996.
   
6. Ann Gibbons, New Feathered Fossil Brings Dinosaurs and Birds Closer, Science 274:720–721, 1996.
   
7. J.D. Sarfati, Kentucky Fried Dinosaur? Creation 19(2):6, March–May 1997.
   
8. New Scientist 154(2077):13, 12 April 1997; Creation 19(3):6, June–August 1997.
   
9. A. Perle et al., Flightless Bird from the Cretaceous of Mongolia, Nature 362:623–626, 1993; note correction of the name to Mononykus, as Perle et al.'s choice, Mononychus, was already taken, Nature 363:188, 1993.
   
10. Time (Australia), 26 April 1993.
    
11. D.P. Prothero and R.M. Schoch, editors, Major Features of Vertebrate Evolution, On the Origin of Birds and of Avian Flight, by J.H. Ostrom (Knoxville, TN: University of Tennessee Press, 1994), p. 160–177.
    
12. Ji Qiang, P.J. Currie, M.A. Norell, and Ji Shu-An, Two Feathered Dinosaurs from Northeastern China, Nature 393(6687):753–761, 25 June 1998. Perspective by K. Padian, same issue, p. 729–730.
    
13. Cited 24 June 1998, CNN website <www.cnn.com>.
    
14. Washington Post, 25 June 1998.
    
15. A. Gibbons, New Feathered Fossil Brings Dinosaurs and Birds Closer, Science 274:720–721, 1996.
    
16. A.C. Burke and A. Feduccia, Developmental Patterns and the Identification of Homologies in the Avian Hand, Science 278(5338):666–8, 24 October 1997, with a perspective by R. Hinchliffe, The Forward March of the Bird-Dinosaurs Halted? p. 596–597; J.D. Sarfati, Dino-Bird Evolution Falls Flat, Creation 20(2):41, March 1998.
    
17. The Cincinnati Enquirer, 25 October 1997.
    
18. P. Shipman, Birds Do It … Did Dinosaurs? New Scientist 153(2067):26–31, 1 February 1997, p. 28.
    
19. Ibid.
    
20. A. Feduccia, The Origin and Evolution of Birds (New Haven, CT: Yale University Press, 1996), p. 130
    
21. Photo courtesy of Dr David Menton.
    
22. R. Dawkins, Climbing Mount Improbable (Harmondsworth, Middlesex, England: Penguin Books, 1996), p. 113.
    
23. A. Feduccia, The Origin and Evolution of Birds (New Haven, CT: Yale University Press, 1996), p. 130.
    
24. A.H. Brush, On the Origin of Feathers, Journal of Evolutionary Biology 9:131142, 1996.
    
25. M. Denton, Evolution, a Theory in Crisis (Bethesda, MD: Adler & Adler, 1985), p. 199–213; K. Schmidt-Nielsen, How Birds Breathe, Scientific American, December 1971, p. 72–79.
    
26. Engineers make much use of this principle of counter-current exchange which is common in living organisms as well—see P.F. Scholander, The Wonderful Net, Scientific American, April 1957, p. 96–107.
    
27. Michael Denton, Blown Away By Design, Creation 21(4):14–15.
    
28. A. Feduccia, The Origin and Evolution of Birds (New Haven, CT: Yale University Press, 1996). However, this book shows that the usual dinosaur-to-bird dogma has many holes.
    
29. Ann Gibbons, New Feathered Fossil Brings Dinosaurs and Birds Closer, Science 274:720–721, 1996.
    
30. K. Padian and L.M. Chiappe, The Origin of Birds and Their Flight, Scientific American 278(2):38–47, February 1998, p. 43

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