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A Middle Miocene Beaked Whale Tooth  (Cetacea: Ziphiidae) from the Carmel Church Quarry, Virginia, and Implications for the Evolution of Sexual Dimorphism in Ziphiids

by Alton C. Dooley, Jr.
published 22 October 2010

ABSTRACT
An apparent right apical mandibular tooth from a beaked whale (Family Ziphiidae) was collected at the Carmel Church Quarry, Caroline County, Virginia in August 2009. The occurrence of this specimen in Bed 15 of the Calvert Formation marks only the second report of a ziphiid from the Calvert Formation. Moreover, this specimen represents, along with the Peruvian Nazcacetus and Messapicetus, the earliest known occurrence of an enlarged mandibular tooth in a ziphiid. The complete closure of the pulp cavity indicates that this tooth derived from a fully mature animal, while the lack of wear on the crown indicates that the tooth had not erupted from the gums, suggesting that the animal was a female. The presence of unerupted mandibular teeth in a fully mature female suggests that, even by the middle Miocene, ziphiids had already evolved modern behavioral patterns in which enlarged mandibular teeth are used exclusively for intraspecific combat between competing males.

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This entry was posted on April 18, 2013 by in Jeffersoniana and tagged , .
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