Maxillary teeth in sperm whales, Physeter macrocephalus (Cetacea: Physeteridae)

Abstract

Sperm whales, Physeter macrocephalus Linnaeus, 1758, have 18 to 28 pairs of well developed conical mandibular teeth, but maxillary teeth are vestigial and supposedly rare. The aim of this study is to report a new case of erupted maxillary teeth in P. macrocephalus, the first description for Brazil. On 29 October 2008 a female sperm whale was found stranded in Campina's Beach (06° 46' S, 34° 55' W), Paraíba state, northeastern Brazil. Inspection on the gums revealed three upper teeth on the right maxilla, corresponded to mandibular teeth 9 to 11 in a rostrocaudal sequence. The maxillary teeth were nearly straight, strongly worn in the tip and had no pulp cavity remaining. Most literature states that maxillary teeth are absent or rarely present, somewhat questionable, since other authors never failed to expose them by an incision in the gum. Data show that upper teeth have been overlooked, and its real frequency can only be determined by thorough dissections. This is important, since the study of maxillary teeth can provide information about evolution, functional morphology and age determination in sperm whales.

Keywords

odontoceti - osteology - stranded - upper teeth