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Re: Pteros might be dinos?!? Oh no ...



To assess how much "crazy" is to think pterosaurs are saurischian or
theropod dinosaurs one should perform a phylogenetic analysis with a
relatively large matrix as that of Brusatte et al. (2008; including
more dinosauriforms and characters relative to their
interrelationships will be useful also) under the constraint of
considering pterosaurs as related to saurischians, and then see how
many more steps has this tree compared with the most parsimonious tree
without the constraint.

Regarding the elongation of penultimate manual phalanges, one should
have care because that elongation also happens in Heterodontosaurus
(Santa Luca, 1980, fig. 13), which is considered by now one of the
most basal ornithischians (Butler et al., 2007). It may be a basal
dinosaur feature. Thin-walled bones are also known in basal
sauropodomorphs as material referred to Thecodontosaurus (Benton et
al., 2000, fig. 16h).

References:

Benton, M. J., Juul, L., Storrs, G. W. y Galton, P. M. 2000. Anatomy
and systematics of the prosauropod dinosaur Thecodontosaurus antiquus
from the Upper Triassic of southwest England. Journal of Vertebrate
Paleontology, 20 (1): 77-10.

Butler, R. J., Smith, R. M. H. y Norman, D. B. 2007. A primitive
ornithischian dinosaur from the Late Triassic of South Africa, and the
early evolution and diversification of Ornithischia. Proceedings of
the Royal Society of London (B), 274: 2041-2046.

Santa Luca, A. P. 1980. The postcranial skeleton of Heterodontosaurus
tucki (Reptilia, Ornithischia) from the Stormberg of South Africa.
Annals of the South African Museum, 79 (7): 159-211.