A new dolphin from the early Miocene of Patagonia (Argentina): insights into the evolution of Platanistoidea in the Southern Hemisphere

MARIANA VIGLINO; MÓNICA R. BUONO; CAROLINA GUTSTEIN; MARIO A. COZZUOL

ACTA PALAEONTOLOGICA POLONICA

INST PALEOBIOLOGII PAN

Lugar: Varsovia; Año: 2018

0567-7920

The contents of the Superfamily Platanistoidea, an early-diverging lineage comprising extinct species and a single extant representative (Platanista gangetica), remain controversial. We describe here a partial skull and associated tympano-periotic bones identified as a new genus and species, Aondelphis talen Viglino, Buono, Gutstein, Cozzuol and Cuitiño gen. et sp. nov., collected in the lower levels of the Gaiman Formation (early Miocene), in Patagonia (Chubut province, Argentina). Aondelphis is the first Patagonian platanistoid species named in almost a century. Phylogenetic analyses suggest Aondelphis talen gen. et sp. nov. and a taxon from New Zealand (cf. Papahu ZMT-73) are basal Platanistoidea sensu lato. Unambiguous synapomorphies related to the ear bones allowed us to determine it phylogenetic position. Aondelphis talen markedly differs from the other well-known early Miocene Patagonian platanistoid Notocetus, suggesting the coexistence of at least two different morphotypes that may have occupied different ecological niches at that time.The putative close relationship with a species from New Zealand indicates there was a rapiddiversification and widespread distribution of the group in the Southern Hemisphere during the early Miocene. The description of new species and revision of historical records of Patagonian platanistoids can help shedding light on cetacean assemblages of the Patagonian sea during this epoch.