Three-dimensional geometric morphometric analysis of the skull of Protoceratops andrewsi supports a socio-sexual signalling role for the ceratopsian frill

Knapp, A.; Knell, R. J.; Hone, D. W.E.

Abstract

Socio-sexual selection is predicted to be an important driver of evolution, influencing speciation, extinction and adaptation. The fossil record provides a means of testing these predictions, but detecting its signature from morphological data alone is difficult. There are, nonetheless, some specific patterns of growth and variation which are expected of traits under socio-sexual selection. The distinctive parietal-squamosal frill of ceratopsian dinosaurs has previously been suggested as a socio-sexual display trait, but evidence for this has been limited. Here, we perform a whole-skull shape analysis of an unprecedentedly large sample of specimens of Protoceratops andrewsi using a high-density landmark-based geometric morphometric approach to test four predictions regarding a potential socio-sexual signalling role for the frill. Three predictions - low integration with the rest of the skull, significantly higher rate of change in size and shape during ontogeny, and higher morphological variance than other skull regions - are supported. One prediction, sexual dimorphism in shape, is not supported, suggesting that sexual differences in P. andrewsi are likely to be small. Together, these findings are consistent with mutual mate choice or selection for signalling quality in more general social interactions, and support the hypothesis that the frill functioned as a socio-sexual signal in ceratopsian dinosaurs.

Citation

Knapp, A., Knell, R. J., & Hone, D. W. (2021). Three-dimensional geometric morphometric analysis of the skull of Protoceratops andrewsi supports a socio-sexual signalling role for the ceratopsian frill. Proceedings of the Royal Society B: Biological Sciences, 288(1944), Article 20202938. https://doi.org/10.1098/rspb.2020.2938

• Journal Article Type: Article
• Acceptance Date: Jan 12, 2021
• Online Publication Date: Feb 3, 2021
• Publication Date: Feb 10, 2021
• Deposit Date: Jul 9, 2023
• Publicly Available Date: Jul 28, 2023
• 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: 1944
• Article Number: 20202938
• DOI: https://doi.org/10.1098/rspb.2020.2938
• Keywords: Evolution; Dinosauria; Geometric morphometrics; Socio-sexual selection
• Public URL: https://hull-repository.worktribe.com/output/4330610