Avian lower jaw clarifies phylogeny near crown bird origin (free pdf)
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Ben Creisler
Dec 25, 2025, 1:06:28 PM (14 days ago) 12/25/25
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Ben Creisler
A new paper:
Abi H. Crane, Juan Benito, Albert Chen, Daniel T. Ksepka & Daniel J. Field (2025)
Mandibular morphology clarifies phylogenetic relationships near the origin of crown birds
BMC Ecology and Evolution (advance online publication)
doi: https://doi.org/10.1186/s12862-025-02487-4
https://link.springer.com/article/10.1186/s12862-025-02487-4
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.
Background
The phylogenetic relationships of fossil birds near the origin of the avian crown group remain debated, in part due to a limited amount of character evidence from incomplete fossils. The avian lower jaw provides a potentially rich source of additional character data, yet fusion of the individual bony elements composing the avian post-dentary complex has impeded efforts to explore its phylogenetic signal. Here, we use high-resolution µCT-scanning to separate the individual bony elements of the mandibles of several immature crown birds and key fossil taxa, and use those data to assess support for alternative phylogenetic hypotheses for fossils near the origin of crown birds.
Results
We find that evidence from Asteriornis fails to support interpretations of derived mandibular similarities with palaeognaths, and instead strongly favours galloanseran, and specifically galliform, affinities. Our results also illustrate striking similarities in the architecture of the lower jaws between the toothed ornithurine Ichthyornis, Pelagornithidae and Vegavis, which, in addition to the absence of derived features linking them to Galloanserae, highlights questions regarding the phylogenetic position of these perennially controversial taxa.
Conclusions
Our data reveal new insight into patterns of morphological evolution near the origin of the avian crown group while raising new phylogenetic questions, emphasising the potential untapped value of detailed comparative investigations of morphological complexes such as the post-dentary complex of the mandible for informing the early evolutionary history of crown birds.
Data availability
The CT datasets generated during the current study are available from the corresponding author on reasonable request.
Free pdf:
Abi H. Crane, Juan Benito, Albert Chen, Daniel T. Ksepka & Daniel J. Field (2025)
Mandibular morphology clarifies phylogenetic relationships near the origin of crown birds
BMC Ecology and Evolution (advance online publication)
doi: https://doi.org/10.1186/s12862-025-02487-4
https://link.springer.com/article/10.1186/s12862-025-02487-4
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.
Background
The phylogenetic relationships of fossil birds near the origin of the avian crown group remain debated, in part due to a limited amount of character evidence from incomplete fossils. The avian lower jaw provides a potentially rich source of additional character data, yet fusion of the individual bony elements composing the avian post-dentary complex has impeded efforts to explore its phylogenetic signal. Here, we use high-resolution µCT-scanning to separate the individual bony elements of the mandibles of several immature crown birds and key fossil taxa, and use those data to assess support for alternative phylogenetic hypotheses for fossils near the origin of crown birds.
Results
We find that evidence from Asteriornis fails to support interpretations of derived mandibular similarities with palaeognaths, and instead strongly favours galloanseran, and specifically galliform, affinities. Our results also illustrate striking similarities in the architecture of the lower jaws between the toothed ornithurine Ichthyornis, Pelagornithidae and Vegavis, which, in addition to the absence of derived features linking them to Galloanserae, highlights questions regarding the phylogenetic position of these perennially controversial taxa.
Conclusions
Our data reveal new insight into patterns of morphological evolution near the origin of the avian crown group while raising new phylogenetic questions, emphasising the potential untapped value of detailed comparative investigations of morphological complexes such as the post-dentary complex of the mandible for informing the early evolutionary history of crown birds.
Data availability
The CT datasets generated during the current study are available from the corresponding author on reasonable request.
Mickey Mortimer
Dec 26, 2025, 6:30:52 PM (13 days ago) 12/26/25
to Dinosaur Mailing Group
Note this unedited version does not contain the figures, although some of these are covered in the supplementary figures.
Also, a preprint of this was posted earlier this year by Ben which does include the figures they intended to use at the time- https://www.biorxiv.org/content/10.1101/2025.09.26.678747v1 .
Also, a preprint of this was posted earlier this year by Ben which does include the figures they intended to use at the time- https://www.biorxiv.org/content/10.1101/2025.09.26.678747v1 .
Mickey Mortimer
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