A new inioid (Cetacea, Odontoceti, Delphinida) from the Miocene of Peru and the origin of modern dolphin and porpoise families

In this paper we describe Brujadelphis ankylorostris gen. nov., sp. nov., a new delphinidan (Cetacea, Odontoceti, Delphinida), based on a well-preserved skull with ear bones, associated mandibles, most of the teeth in situ and a fragment of the atlas, from the late middle to early late Miocene (Serravallian to early Tortonian) of the Pisco Formation, Pisco Basin, Peru. The new taxon differs from all other delphinidans in the following unique combination of character states: partial ankylosis of the thickened premaxillae above the mesorostral groove; presence of premaxillary eminences; premaxilla does not contact nasal; inflated nasals with a transversely convex dorsal surface; presence of an internasal fossa; and a longitudinal crest on the vertex formed by transversely pinched frontals. Our cladistic analyses of a supermatrix that includes molecular and morphological data identifies B. ankylorostris as an inioid (Iniidae + Pontoporiidae) that is more closely related to Inia than to Pontoporia. This result persists even if a molecular scaffold based on published Bayesian analyses is used. The inclusion of a large sample (12 taxa) of ‘kentriodontids’ allows us to confirm the paraphyly of this group of archaic Miocene delphinidans but contradicts the prevailing views in placing all of these taxa outside of Delphinoidea (Delphinidae + Monodontidae + Phocoenidae). In our unconstrained analysis ‘kentriodontids’ are split into five separate clades that occur along the stem of Inioidea + Delphinoidea. Based on our most parsimonious trees, we discuss published calibration points for molecular divergence estimates within Odontoceti and propose one new point: 18 Ma for an unnamed clade including Delphinida + Ziphiidae.