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Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2006
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Claim CB731:

Most scientists believe that birds descended from theropod dinosaurs. But theropod dinosaurs have lost digits IV and V from a primitively five-fingered hand, leaving them with digits I, II, and III. Birds, on the other hand, have digits II, III, and IV, having lost digits I and V (Feduccia and Nowicki 2002). It is almost impossible for the two groups to be closely related with such a significant anatomical difference.

Source:

Sarfati, Jonathan, 2002. Ostrich eggs break dino-to-bird theory. Creation 25(1): 34-35. http://www.answersingenesis.org/docs2002/0822_ostrich_dino.asp

Response:

  1. Anatomists initially thought bird digits were I, II, II based on their anatomy. This was revised on the basis of bird embryology; the digits are seen to derive from condensations II, III, IV. It is plausible that dinosaur digits also developed from condensations II, III, IV, and a frame shift in the development of digit identity causes those three condensations to developed into digits I, II, III. Such a frameshift occurs in kiwis, in which digits II, III take the form of I, II with the loss of the condensation for digit I (Wagner and Gauthier 1999).

Links:

Myers, P. Z. 2004. Digit numbering and limb development. http://pharyngula.org/index/weblog/comments/digit_numbering_and_limb_development/

References:

  1. Feduccia, A. and J. Nowicki. 2002. The hand of birds revealed by early ostrich embryos. Naturwissenschaften 89: 391-393.
  2. Wagner, G. P. and J. A. Gauthier. 1999. 1,2,3=2,3,4: A solution to the problem of the homology of the digits in the avian hand. Proceedings of the National Academy of Science USA 96: 5111-5116.

Further Reading:

Pennisi, Elizabeth. 2005. Bird wings really are like dinosaurs' hands. Science 307: 194-195.
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created 2004-9-17, modified 2006-9-7