Kogia pusilla from the Middle Pliocene of Tuscany (Italy) and a Phylogenetic analysis of the family Kogiidae (Odontoceti, Cetacea)

A partial skull of an odontocete cetacean from Middle Pliocene sediments of Monte Voltraio (Pisa Province, Tuscany, Italy) is examined. This fossil, e rroneously referred to the family Ziphiidae and described in the past as ho lotype of the species Hyperoodon pusillus, is assigned here to the genus Ko gia (family Kogiidae). The species Kogia pusilla is redescribed and compare d to the living species K. breviceps and K, simus. Phylogenetically, an old separation (at least in the Lower Miocene) of Kogi idae and Physeteridae is suggested. The lack of substantiated kogiid record s until the Upper Miocene is probably due to the rarity of these cetaceans. Phyletic analysis within the Kogiidae is undertaken and supposed apomorphi es in the morphology and/or the extension of the supracranial basin that ho uses the large air sacs and the spermaceti organ are considered.