Beaked Whale Identification Guide
Diagnostic features of the skull and mandible
On the vertex of the dorsal skull the nasal bone extends forward of the premaxillary and frontal bones. Separates from Indopacetus, Mesoplodon, and Tasmacetus.

When the posterior aspect of the skull is viewed from a point aligned with the long axis of the rostrum, the profile of the vertex is completely occluded by the supraoccipital , or so little of the vertex shows that the profile of descending sides of the vertex are not visible. Separates from Berardius.

Adult males have a sexually dimorphic feature, the prenarial basin found on the dorsal aspect of the skull just anterior to the external bony nares. This feature is the result of resorption of bone from the premaxillaries, maxillaries, and vomer.
Ziphius cavirostris - Ventral mandible
Adult male - USNM 550122 (left)
Adult female - USNM - 530291 (right)
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