Daniel Philippe
Well-known member
Do not remember having seen this paper before:
http://www.bio.fsu.edu/James/Ornithological Monographs 2009.pdf
http://www.bio.fsu.edu/James/Ornithological Monographs 2009.pdf
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Cladistics and the origin of birds (1 Viewer)
- Thread starter Daniel Philippe
- Start date
Mysticete
Well-known member
There probably is a good reason why you haven't heard much from this, and that is because it is a deeply flawed study.
Darren Naish has summarized the flaws in a post here:
http://scienceblogs.com/tetrapodzoology/2010/06/gary_kaisers_the_inner_bird.php
"As for James & Pourtless (2009): these authors use cladistics to test the hypothesis that birds are deeply nested within coelurosaurian theropods, and argue that they use an unbiased approach where non-dinosaurian archosaurs and other reptiles are included too (they include Longisquama among archosaurs for some reason, and even imply that it's a proto-bird [p. 37]). The paper is full of really weird claims (e.g., that theropods can only be diagnosed by their intramandibular joint) and does a lot of stuff that's bound to skew the results: they coded all characters of disputed homology as 'unknown' (p. 14), for example (and, as usual among those disputing the theropod affinities of birds, they ignore evidence showing that the disputes about homology are erroneous anyway). This is wrong because it makes an a priori assumption about homology, and it introduces loads of new question marks in the matrix for character states where we do have data. Furthermore, the choice of taxa is weird: it's wrong to analyse theropods and other archosaurs without including at least some non-theropod dinosaurs. Finally, the trees they generated are entirely uninformative (they are mostly polytomies) and don't provide support for any hypothesis, so quite how the authors can say that they found weaknesses in the 'birds are theropods' hypothesis is really not apparent. As an impartial test of archosaur phylogeny, this study fails miserably."
There are more links on the excellent Tetrapod Zoology dealing with subject:
http://scienceblogs.com/tetrapodzoology/2009/06/birds_come_first_hypothesis.php
http://scienceblogs.com/tetrapodzoology/2009/07/birds_cannot_be_dinosaurs.php
Darren Naish has summarized the flaws in a post here:
http://scienceblogs.com/tetrapodzoology/2010/06/gary_kaisers_the_inner_bird.php
"As for James & Pourtless (2009): these authors use cladistics to test the hypothesis that birds are deeply nested within coelurosaurian theropods, and argue that they use an unbiased approach where non-dinosaurian archosaurs and other reptiles are included too (they include Longisquama among archosaurs for some reason, and even imply that it's a proto-bird [p. 37]). The paper is full of really weird claims (e.g., that theropods can only be diagnosed by their intramandibular joint) and does a lot of stuff that's bound to skew the results: they coded all characters of disputed homology as 'unknown' (p. 14), for example (and, as usual among those disputing the theropod affinities of birds, they ignore evidence showing that the disputes about homology are erroneous anyway). This is wrong because it makes an a priori assumption about homology, and it introduces loads of new question marks in the matrix for character states where we do have data. Furthermore, the choice of taxa is weird: it's wrong to analyse theropods and other archosaurs without including at least some non-theropod dinosaurs. Finally, the trees they generated are entirely uninformative (they are mostly polytomies) and don't provide support for any hypothesis, so quite how the authors can say that they found weaknesses in the 'birds are theropods' hypothesis is really not apparent. As an impartial test of archosaur phylogeny, this study fails miserably."
There are more links on the excellent Tetrapod Zoology dealing with subject:
http://scienceblogs.com/tetrapodzoology/2009/06/birds_come_first_hypothesis.php
http://scienceblogs.com/tetrapodzoology/2009/07/birds_cannot_be_dinosaurs.php
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