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Craniofacial development illuminates the evolution of nightbirds (Strisores)

Navalón, Guillermo; Nebreda, Sergio M.; Bright, Jen A.; Fabbri, Matteo; Benson, Roger B. J.; Bhullar, Bhart Anjan; Marugán-Lobón, Jesús; Rayfield, Emily J.


Guillermo Navalón

Sergio M. Nebreda

Matteo Fabbri

Roger B. J. Benson

Bhart Anjan Bhullar

Jesús Marugán-Lobón

Emily J. Rayfield


Evolutionary variation in ontogeny played a central role in the origin of the avian skull. However, its influence in subsequent bird evolution is largely unexplored. We assess the links between ontogenetic and evolutionary variation of skull morphology in Strisores (nightbirds). Nightbirds span an exceptional range of ecologies, sizes, life-history traits and craniofacial morphologies constituting an ideal test for evo-devo hypotheses of avian craniofacial evolution. These morphologies include superficially 'juvenile-like' broad, flat skulls with short rostra and large orbits in swifts, nightjars and allied lineages, and the elongate, narrow rostra and globular skulls of hummingbirds. Here, we show that nightbird skulls undergo large ontogenetic shape changes that differ strongly from widespread avian patterns. While the superficially juvenile-like skull morphology of many adult nightbirds results from convergent evolution, rather than paedomorphosis, the divergent cranial morphology of hummingbirds originates from an evolutionary reversal to a more typical avian ontogenetic trajectory combined with accelerated ontogenetic shape change. Our findings underscore the evolutionary lability of cranial growth and development in birds, and the underappreciated role of this aspect of phenotypic variability in the macroevolutionary diversification of the amniote skull.


Navalón, G., Nebreda, S. M., Bright, J. A., Fabbri, M., Benson, R. B. J., Bhullar, B. A., …Rayfield, E. J. (2021). Craniofacial development illuminates the evolution of nightbirds (Strisores). Proceedings of the Royal Society B: Biological Sciences, 288(1948), Article 20210181.

Journal Article Type Article
Acceptance Date Mar 17, 2021
Online Publication Date Apr 14, 2021
Publication Date Apr 14, 2021
Deposit Date Apr 14, 2021
Publicly Available Date Oct 27, 2022
Journal Proceedings of the Royal Society B: Biological Sciences
Print ISSN 0962-8452
Electronic ISSN 1471-2954
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 288
Issue 1948
Article Number 20210181
Keywords Skull; Birds; Ontogeny; Shape; Morphometrics; Macroevolution
Public URL


Published article (1.1 Mb)

Copyright Statement
© 2021 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License, which permits unrestricted use, provided the original author and source are credited.

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