Skip to main content

Research Repository

Advanced Search

Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus

Elton, S.; Morgan, B.J.

Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus Thumbnail


B.J. Morgan


The drill (Mandrillus leucophaeus), a forest-living Old World monkey, is highly sexually dimorphic, with males exhibiting extreme secondary sexual characteristics, including growth of paranasal swellings on the muzzle. In this study, the size of the secondary bone that forms the paranasal swellings on the muzzles of drills was assessed in relation to body mass proxies. The relationship between the overall size of the muzzle and surrogate measures of body mass was also examined. In female drills, muzzle breadth was positively correlated with two proxies of overall body mass, greatest skull length and upper M1 area. However, there was no such correlation in males. Paranasal swellings in males also appeared to have no significant relationship to body mass proxies. This suggests that secondary bone growth on the muzzles of male drills is independent of overall body size. Furthermore, this secondary bone appears to be vermiculate, probably developing rapidly and in an irregular manner, with no correlation in the sizes of paranasal swelling height and breadth. However, various paranasal swelling dimensions were related to the size of the muzzle. It is suggested that the growth of the paranasal swellings and possibly the muzzle could be influenced by androgen production and reflect testes size and sperm motility. The size and appearance of the paranasal swellings may thus be an indicator of reproductive quality both to potential mates and male competitors. Further work is required to investigate the importance of the paranasal swellings as secondary sexual characteristics in Mandrillus and the relationship between body size and secondary sexual characteristics. Attention should also be paid to the mechanisms and trajectories of facial growth in Mandrillus.


Elton, S., & Morgan, B. (2006). Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus. Primates, 47(2), 151-157.

Journal Article Type Article
Acceptance Date Aug 23, 2005
Publication Date Apr 1, 2006
Deposit Date May 23, 2013
Publicly Available Date Dec 7, 2015
Journal Primates
Print ISSN 0032-8332
Electronic ISSN 1610-7365
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 47
Issue 2
Pages 151-157
Keywords Drill, Mandrill, Cercopithecidae, Muzzle, Craniofacial morphology, Body size.


Accepted Journal Article (476 Kb)

Copyright Statement
The final publication is available at Springer via

You might also like

Downloadable Citations