Shape analysis of odontocete mandibles: Functional and evolutionary implications
Article first published online: 13 JUL 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Morphology
Volume 273, Issue 9, pages 1021–1030, September 2012
How to Cite
Barroso, C., Cranford,, T. W. and Berta, A. (2012), Shape analysis of odontocete mandibles: Functional and evolutionary implications. J. Morphol., 273: 1021–1030. doi: 10.1002/jmor.20040
- Issue published online: 8 AUG 2012
- Article first published online: 13 JUL 2012
- Manuscript Accepted: 6 APR 2012
- Manuscript Revised: 16 MAR 2012
- Manuscript Received: 16 NOV 2011
- geometric morphometrics
Odontocete mandibles serve multiple functions, including feeding and hearing. We consider that these two major functions have their primary influence in different parts of the mandibles: the anterior feeding component and the posterior sound reception component, though these divisions are not mutually exclusive. One hypothesis is that sound enters the hearing apparatus via the pan bone of the posterior mandibles (Norris, Evolution and Environment,1968, pp 297–324). Another viewpoint, based on finite element models, suggests that sound enters primarily through the gular region and the opening created by the absent medial lamina of the posterior mandibles. This unambiguous link between form and function has catalyzed this study, which uses Geometric Morphometrics to quantify mandibular shape across all major lineages of Odontoceti. The majority of shape variation was found in the anterior (feeding) region: Jaw Flare (45.0%) and Symphysis Elongation (35.5%). Shape differences in the mandibular foramen, within the posterior (sound reception) region, also accounted for a small portion of the total variation (10.9%). The mandibles are an integral component of the sound reception apparatus in toothed whales and the geometry of the mandibular foramen likely plays a role in hearing. Furthermore, model goodness-of-fit tests indicate that mandibular foramina shapes, which appear conserved, evolved under a selective regime, possibly driven by sound reception requirements across Odontoceti. J. Morphol. © 2012 Wiley Periodicals, Inc.