GROWTH LAYERS IN TEETH FROM KNOWN-AGE, FREE-RANGING BOTTLENOSE DOLPHINS

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Abstract

Growth layers were examined in teeth collected from free-ranging bottlenose dolphins, Tursiops truncatus, from Florida that have been part of a long-term study begun in 1970; 26 of the dolphins were of known or approximately known age, and 19 were of minimum known age. A second tooth was extracted from 6 animals for examination of growth that had taken place in the interval following the initial extraction. The teeth were read for age estimates without knowledge of any data pertaining to the animals. Most of the estimated ages were the same as or close to the known and approximately known ages of the animals, ranging from 2 to 16 yr. We conclude that the structures we define as dentinal growth layer groups (GLGs) are annual, we describe sources of error in age estimates, and we provide a description of the GLG pattern that can be used by others to estimate age for dolphins.

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