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Sci Rep. 2014 Aug 13;4:6042. doi: 10.1038/srep06042.

Homologies and homeotic transformation of the theropod 'semilunate' carpal.

Author information

1
Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology &Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044.
2
Faculty of Earth Sciences, China University of Geosciences, No. 388 Lumo Road, Wuhan 430074, People's Republic of China.

Abstract

The homology of the 'semilunate' carpal, an important structure linking non-avian and avian dinosaurs, has been controversial. Here we describe the morphology of some theropod wrists, demonstrating that the 'semilunate' carpal is not formed by the same carpal elements in all theropods possessing this feature and that the involvement of the lateralmost distal carpal in forming the 'semilunate' carpal of birds is an inheritance from their non-avian theropod ancestors. Optimization of relevant morphological features indicates that these features evolved in an incremental way and the 'semilunate' structure underwent a lateral shift in position during theropod evolution, possibly as a result of selection for foldable wings in birds and their close theropod relatives. We propose that homeotic transformation was involved in the evolution of the 'semilunate' carpal. In combination with developmental data on avian wing digits, this suggests that homeosis played a significant role in theropod hand evolution in general.

PMID:
25116378
PMCID:
PMC4131224
DOI:
10.1038/srep06042
[Indexed for MEDLINE]
Free PMC Article

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