eprintid: 1555783 rev_number: 35 eprint_status: archive userid: 608 dir: disk0/01/55/57/83 datestamp: 2017-09-26 13:41:56 lastmod: 2021-09-26 22:16:24 status_changed: 2017-09-26 13:41:56 type: article metadata_visibility: show creators_name: Balolia, KL creators_name: Soligo, C creators_name: Wood, B title: Sagittal crest formation in great apes and gibbons ispublished: pub divisions: UCL divisions: B03 divisions: C03 divisions: F22 keywords: Cranium; ectocranial cresting; hominoid; sexual dimorphism; sexual selection note: © 2017 Anatomical Society. This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: The frequency of sagittal crest expression and patterns of sagittal crest growth and development have been documented in hominoids, including some extinct hominin taxa, and the more frequent expression of the sagittal crest in males has been traditionally linked with the need for larger-bodied individuals to have enough attachment area for the temporalis muscle. In the present study, we investigate sagittal cresting in a dentally mature sample of four hominoid taxa (Pan troglodytes schweinfurthii, Gorilla gorilla gorilla, Pongo pygmaeus pygmaeus and Hylobates lar). We investigate whether sagittal crest size increases with age beyond dental maturity in males and females of G. g. gorilla and Po. pyg. pygmaeus, and whether these taxa show sex differences in the timing of sagittal crest development. We evaluate the hypothesis that the larger sagittal crest of males may not be solely due to the requirement for a larger surface area than the un-crested cranial vault can provide for the attachment of the temporalis muscle, and present data on sex differences in temporalis muscle attachment area and sagittal crest size relative to cranial size. Gorilla g. gorilla and Po. pyg. pygmaeus males show significant relationships between tooth wear rank and sagittal crest size, and they show sagittal crest size differences between age groups that are not found in females. The sagittal crest emerges in early adulthood in the majority of G. g. gorilla males, whereas the percentage of G. g. gorilla females possessing a sagittal crest increases more gradually. Pongo pyg. pygmaeus males experience a three-fold increase in the number of specimens exhibiting a sagittal crest in mid-adulthood, consistent with a secondary growth spurt. Gorilla g. gorilla and Po. pyg. pygmaeus show significant sex differences in the size of the temporalis muscle attachment area, relative to cranial size, with males of both taxa showing positive allometry not shown in females. Gorilla g. gorilla males also show positive allometry for sagittal crest size relative to cranial size. Our results suggest that although patterns of sagittal crest expression have limited utility for taxonomy and phylogeny reconstruction, they could be useful for reconstructing aspects of social behaviour in some extinct hominin taxa. In particular, our results in G. g. gorilla and Po. pyg. pygmaeus, which suggest that the size of sagittal crests in males cannot be solely explained by the surface area required for attachment of the temporalis muscle, offer partial support for the hypothesis that large sagittal crests form in response to sexual selection and may play a role in social signalling. date: 2017-06 date_type: published official_url: http://doi.org/10.1111/joa.12609 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green article_type_text: Journal Article verified: verified_manual elements_id: 1294326 doi: 10.1111/joa.12609 lyricists_name: Soligo, Christophe lyricists_id: CSOLI59 actors_name: Soligo, Christophe actors_name: Laslett, David actors_id: CSOLI59 actors_id: DLASL34 actors_role: owner actors_role: impersonator full_text_status: public publication: Journal of Anatomy volume: 230 number: 6 pagerange: 820-832 issn: 1469-7580 citation: Balolia, KL; Soligo, C; Wood, B; (2017) Sagittal crest formation in great apes and gibbons. Journal of Anatomy , 230 (6) pp. 820-832. 10.1111/joa.12609 <https://doi.org/10.1111/joa.12609>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1555783/1/Soligo_Balolia%20et%20al%202017%20for%20RPS.pdf