Samaydelphis chacaltanae is an extinct genus of dolphin that lived in Peru during the Late Miocene [1]
Decription & Discovery
Part of the late Miocene to Pliocene inioid fossil record is made of relatively fragmentarily known species, for which systematic affinities remain poorly understood. Based on a sample of six cranial specimens from early late Miocene (Tortonian, 9.5-8.6 Ma) marine deposits of the Pisco Formation in four localities of the East Pisco Basin (southern coast of Peru), paleontologists have officially describe a new genus and species of inioid, Samaydelphis chacaltanae.
Bearing a proportionally short rostrum with an upper tooth count of about 30 teeth per row, this small-sized species is characterized by a moderately elevated vertex of the cranium displaying a long anteromedial projection of the frontals and interparietal, as well as by the plesiomorphic retention of a premaxilla-nasal contact. Recovered as a member of the family Pontoporiidae in our phylogenetic analysis, S. chacaltanae falls as sister-group to Meherrinia isoni, from the late Miocene of North Carolina (U.S.A.), which has previously been tentatively referred to the Iniidae or regarded as a stem Inioidea. Originating from the P1 allomember of the Pisco Formation, the mesorostrine S. chacaltanae was contemporaneous and sympatric with two other inioids, the brevirostrine pontoporiid Brachydelphis mazeasi and the longirostrine iniid Brujadelphis ankylorostris. [2]