MAKE A MEME View Large Image Bird and dino hand difference debate.JPG en Diagram made to illustrate the debate over the hands of theropod dinosaurs and their alleged descendants the birds Aves In the last years the difference between the hands of theropods and birds ...
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Keywords: Bird and dino hand difference debate.JPG en Diagram made to illustrate the debate over the hands of theropod dinosaurs and their alleged descendants the birds Aves In the last years the difference between the hands of theropods and birds have been an important thing when it comes question the theory that birds evolved from dinosaurs even though some scientists may could refute it In the diagram a Neotheropoda 1 basal tetanurae 2 a coelurosaurian 3 the bird Archaeopteryx 4 and modern bird 5 In 1997 birdexpert Alan Feduccia at University of North Carolina discovered that birds develop hands with the digits II III and IV see The Cincinnati Enquirer 25 - 10 - 1997 This is in contrast with the hands of tetanurae which seems to have the digits I II and III This make it almost impossible for dinosaurs and birds to be closely related according to Feduccia Since the discovery by Feduccia scientific research have came up with a possible explanation to the mystery of the dinosaur - bird hand difference called The frame shift hypothesis see http //scienceblogs com/tetrapodzoology/2009/06/limusaurus_is_awesome php This hypothesis is based on a discovery which shows that although bird embryos develop the fingers II III and IV the genes which is coding for the external appearance of the digits seems to be from the fingers I II and III Based on this scientists belive this when neotheropods evolved into tetanurae the losed digit I not digit IV as earlier suggested During this process the genes which coded for how the digits should looks like the number of phalanges for example became refurnished see the color spots in th upper section in the diagram to understan The discovery of Limusaurus has been said to support this theory see http //www livescience com/animals/090617-dinosaur-hands html One thing is that may can be used to refute that Limusaurus should support the Frame shift hypothesis is that Limusaurus was a ceratosaurian and is dated to be much younger than the oldest tetanurae's Also some tetanureĀ“s may had 4 digits' like the Archaeornithomimus see number 4 in the diagram see also http //dml cmnh org/1998Oct/msg00443 html and the Allosaurus hand in the image here http //upload wikimedia org/wikipedia/commons/6/69/Allosaurus-mounted jpg If this is the digits I II III and IV If so it shows that tetanurae had the digits I II and III and not II II and IV like birds For more in this debate see text section to my picture Raptor-Archaeopteryx-bird hands differens JPG at http //commons wikimedia org/wiki/File Raptor-Archaeopteryx-bird_hands_differens JPG own Conty Archosauria Bird wing bones Reptilia limb bones Animal limb bone comparisons
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