Comparative morphology of porpoise (Cetacea: Phocoenidae) pterygoid sinuses: Phylogenetic and functional implications
Article first published online: 11 SEP 2012
Copyright © 2012 Wiley Periodicals, Inc.
Journal of Morphology
Volume 274, Issue 1, pages 49–62, January 2013
How to Cite
Racicot, R. A. and Berta, A. (2013), Comparative morphology of porpoise (Cetacea: Phocoenidae) pterygoid sinuses: Phylogenetic and functional implications. J. Morphol., 274: 49–62. doi: 10.1002/jmor.20075
- Issue published online: 5 DEC 2012
- Article first published online: 11 SEP 2012
- Manuscript Accepted: 7 AUG 2012
- Manuscript Revised: 30 JUL 2012
- Manuscript Received: 14 NOV 2011
- San Diego State University Research, Scholarship and Creative Activity Grant (to AB)
- Orange County Chapter of the American Cetacean Society Student Grant (to RAR)
High-resolution X-ray computed tomographic scans were used to examine pterygoid sinus morphology within extant porpoise species and one delphinid (Tursiops truncatus), in order to consider: 1) intraspecific and interspecific variation among the studied species; 2) the most parsimonious sequence of character acquisition; and 3) the potential functional roles of the preorbital lobes of the sinuses in sound reflection. Scans revealed that the pterygoid/palatine regions are mediolaterally broader in the earliest diverging phocoenid (Neophocaena phocaenoides) and Tursiops truncatus than the dorsoventrally elongated sinuses observed in other species. Rostrocaudal lengths of the sphenoidal regions of the sinuses in all individuals studied are proportionally similar, indicating conservatism in this region across species. The neonate Phocoena phocoena has shorter preorbital lobes than adults, but they are still proportionally longer than Neophocaena phocaenoides and Phocoena spinipinnis. The preorbital lobes broaden mediolaterally to varying degrees across species; in particular, Phocoenoides dalli has the largest dorsal and lateral expansion of this region. Assuming the highest pulse frequency produced by porpoises is 150 kHz, all regions of the preorbital lobes are thick enough to reflect the wavelengths produced. In addition, the neonate preorbital lobes are not as elongated as they are in adults, and the dorsal third of this region may not reflect sound to the same extent. This study reinforces the importance of using nondestructive methods to quantify variation in endocranial anatomy and the value of CT data for recovering phylogenetically useful information, as well as functional roles sinuses play in concert with the soft tissue head anatomy for biosonar. J. Morphol. 2013. © 2012 Wiley Periodicals, Inc.