Ratite digit evolution + amniote complex axial skeleton evolution (free pdfs)
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Ben Creisler
Apr 16, 2026, 1:56:14 PM (10 days ago) Apr 16
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Ben Creisler
New papers:
Free pdf:
Wen Kang, Günter Wagner & Qi Zhou (2026)
Degeneration and adaptive evolution of digits in ratite birds
Molecular Biology and Evolution, msag101
doi: https://doi.org/10.1093/molbev/msag101
https://academic.oup.com/mbe/advance-article/doi/10.1093/molbev/msag101/8654147
The amniote digits have undergone recurrent modifications with the diversified molecular mechanisms more studied among mammals than reptiles. Here we focus on the emu wings and ostrich feet, both of which experienced species specific digit changes driven respectively by secondary flight loss and adaptation to running. By comparing their digit transcriptomes to those of chicken and alligator, we identified different gene networks in skeleton/muscle development responsible for the degenerated digits in archosaur ancestor and emu, but those in epidermal development for the load-bearing digit of ostrich. These results provide new clues for developmental programs of different cell types between different digits, on which natural selection can convergently operate.
Wen Kang, Günter Wagner & Qi Zhou (2026)
Degeneration and adaptive evolution of digits in ratite birds
Molecular Biology and Evolution, msag101
doi: https://doi.org/10.1093/molbev/msag101
https://academic.oup.com/mbe/advance-article/doi/10.1093/molbev/msag101/8654147
The amniote digits have undergone recurrent modifications with the diversified molecular mechanisms more studied among mammals than reptiles. Here we focus on the emu wings and ostrich feet, both of which experienced species specific digit changes driven respectively by secondary flight loss and adaptation to running. By comparing their digit transcriptomes to those of chicken and alligator, we identified different gene networks in skeleton/muscle development responsible for the degenerated digits in archosaur ancestor and emu, but those in epidermal development for the load-bearing digit of ostrich. These results provide new clues for developmental programs of different cell types between different digits, on which natural selection can convergently operate.
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Free pdf:
Lucy E. Roberts & Jason J. Head (2026)
Evolution of the reptile spine reveals independent trajectories to axial skeletal complexity in amniotes
Nature Communications (advance online publication)
doi: https://doi.org/10.1038/s41467-026-72071-x
https://www.nature.com/articles/s41467-026-72071-x
[We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.]
The evolution of complex, highly regionalized and heterogeneous axial skeletons within amniotes has traditionally been considered a unique characteristic of Pan-Mammalia, with limited complexity evolving independently in some reptiles. The ability to resolve axial skeletal evolution across Amniota remains restricted due to the lack of studies comprehensively exploring axial skeletal complexity through deep time outside of Pan-Mammalia. Here, we combine 3D geometric morphometrics of vertebral morphology with maximum likelihood model testing in a phylogenetic context to quantify regionalization and morphological heterogeneity in the presacral vertebral column of reptiles and representative tetrapod outgroups. We recover evidence for the evolution of four regions at least four times independently within amniotes, highly heterogeneous axial skeletal anatomies in archosaurs, and no evidence for uniquely complex vertebral anatomies in mammals. Heterogeneity is positively associated with body size in most reptile clades except for theropod dinosaurs, which also reduce regionalization toward the avian crown. The evolution of volancy is correlated with high heterogeneity, potentially associated with functional modularity of the cervical and dorsal regions. Our results indicate that complex axial skeletons arose independently and repeatedly in reptiles in addition to mammals, variably associated with the remarkable diversity in size, body form, function, and ecology across amniotes.
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Lucy E. Roberts & Jason J. Head (2026)
Evolution of the reptile spine reveals independent trajectories to axial skeletal complexity in amniotes
Nature Communications (advance online publication)
doi: https://doi.org/10.1038/s41467-026-72071-x
https://www.nature.com/articles/s41467-026-72071-x
[We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.]
The evolution of complex, highly regionalized and heterogeneous axial skeletons within amniotes has traditionally been considered a unique characteristic of Pan-Mammalia, with limited complexity evolving independently in some reptiles. The ability to resolve axial skeletal evolution across Amniota remains restricted due to the lack of studies comprehensively exploring axial skeletal complexity through deep time outside of Pan-Mammalia. Here, we combine 3D geometric morphometrics of vertebral morphology with maximum likelihood model testing in a phylogenetic context to quantify regionalization and morphological heterogeneity in the presacral vertebral column of reptiles and representative tetrapod outgroups. We recover evidence for the evolution of four regions at least four times independently within amniotes, highly heterogeneous axial skeletal anatomies in archosaurs, and no evidence for uniquely complex vertebral anatomies in mammals. Heterogeneity is positively associated with body size in most reptile clades except for theropod dinosaurs, which also reduce regionalization toward the avian crown. The evolution of volancy is correlated with high heterogeneity, potentially associated with functional modularity of the cervical and dorsal regions. Our results indicate that complex axial skeletons arose independently and repeatedly in reptiles in addition to mammals, variably associated with the remarkable diversity in size, body form, function, and ecology across amniotes.
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