[MARMAM] New publication
rracicot at nhm.org
Fri Aug 5 01:30:27 PDT 2016
Dear MARMAM readers,
We are pleased to announce the publication (available via early view) of the following paper in Biological Journal of the Linnean Society:
"Comparative anatomy of the bony labyrinth of extant and extinct porpoises (Cetacea: Phocoenidae)"
Rachel A. Racicot, William Gearty, Naoki Kohno, John J. Flynn
The inner ear anatomy of cetaceans, now more readily accessible by means of nondestructive high-resolution X-ray computed tomographic (CT) scanning, provides a window into their acoustic abilities and ecological preferences. Inner ear labyrinths also may be a source for additional morphological characters for phylogenetic analyses. In this study, we explore digital endocasts of the inner ear labyrinths of representative species of extinct and extant porpoises (Mammalia: Cetacea: Phocoenidae), a clade of some of the smallest odontocete cetaceans, which produce some of the highest-frequency clicks for biosonar and communication. Metrics used to infer hearing ranges based on cochlear morphology indicate that all taxa considered could hear high-frequency sounds, thus the group had already acquired high-frequency hearing capabilities by the Miocene (9–11 Mya) at the latest. Vestibular morphology indicates that extant species with pelagic preferences have similarly low semicircular canal deviations from 90°, values indicating more sensitivity to head rotations. Species with near-shore preferences have higher canal deviation values, indicating less sensitivity to head rotations. Extending these analyses to the extinct species, we demonstrate a good match between those predicted to have coastal (such as Semirostrum cerutti) preferences and high canal deviation values. We establish new body length relationships based on correlations with inner ear labyrinth volume, which can be further explored among other aquatic mammals to infer body size of specimens consisting of fragmentary material.
Full text available at:
PDFs may be requested from rracicot at nhm.org, although email response may be slow due to field work.
Rachel Racicot, PhD
Postdoctoral Research Scientist
The Dinosaur Institute
Natural History Museum of Los Angeles County
Los Angeles, CA 90007
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