Aquatic Habits of Cetacean Ancestors: Integrating Bone Microanatomy and Stable Isotopes.

Aquatic Habits of Cetacean Ancestors: Integrating Bone Microanatomy and Stable Isotopes.

Cooper Lisa Noelle; Clementz Mark T; Usip Sharon; Bajpai Sunil; Hussain S Taseer; Hieronymus Tobin L

Integrative and comparative biology

2016

2016-12

The earliest cetaceans were interpreted as semi-aquatic based on the presence of thickened bones and stable oxygen isotopes in tooth enamel. However, the origin of aquatic behaviors in cetacean relatives (e.g., raoellids, anthracotheres) remains unclear. This study reconstructs the origins of aquatic behaviors based on long bone microanatomy and stable oxygen isotopes of tooth enamel in modern and extinct cetartiodactylans. Our findings are congruent with published accounts that microanatomy can be a reliable indicator of aquatic behaviors in taxa that are obligatorily aquatic, and also highlight that some "semi-aquatic" behaviors (fleeing into the water to escape predation) may have a stronger relationship to bone microanatomy than others (herbivory in near-shore aquatic settings). Bone microanatomy is best considered with other lines of information in the land-to-sea transition of cetaceans, such as stable isotopes. This study extends our understanding of the progression of skeletal phenotypes associated with habitat shifts in the relatives of cetaceans.

*Ecosystem; Animals; Bone and Bones/anatomy & histology/metabolism; Cetacea/*physiology; Isotope Labeling; Isotopes/metabolism

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1370–1384

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