Chilcacetus

Chilcacetus is an extinct genus of primitive odontocete known from Early Miocene (Aquitanian) of Peru. Fossils were found in and named after the Chilcatay Formation of the Pisco Basin.
Classification.
"Chilcacetus" is recovered along it with the putative eurhinodelphinids "Argyrocetus" and "Macrodelphinus" in a clade basal to "Eoplatanista" and Eurhinodelphinidae. The authors stressed that updated osteological descriptions of "Argyrocetus" and "Macrodelphinus" are necessary to provide more cladistic analysis support for this grouping.
Description.
The teeth of "Chilcacetus" are homodont in nature, and the rostrum is long. The presence of a cavity between nasals and mesethmoid on the posterior wall of the bony nares that distinguishes this taxon from other archaic odontocetes, hence the species name "cavirhinus". The dorsal surface of the nasal rising anterodorsally, extended edentulous anterior premaxillary portion of the rostrum, and a cranium distinctly shorter than wide unite "Chilcacetus" with "Argyrocetus" and "Macrodelphinus" to the exclusion of all other homodont odontocetes, including eurhinodelphinids.