A systematic revision of Preaulophyseter gualichensis (Cetacea, Odontoceti, Physeteroidea) from Argentinian Patagonia, and the phylogenetic signal of tympano-periotics in Physeteroidea

FLORENCIA PAOLUCCI; MÓNICA BUONO; MARTA S. FERNÁNDEZ

Virtual

Congreso; 64th Annual Meeting of the Palaeontological Association -Virtual Meeting; 2020

Sperm whales (Physeteroidea) are known today from only two genera of disparateodontocetes: the largest toothed whale known (Physeter macrocephalus) and small-sizedforms (Kogia spp.). In contrast, their fossil record indicates a high diversity during theMiocene, which is well documented in the marine sediments of Patagonia, Argentina.At least five species are identified, among which is Preaulophyseter gualichensis, from theGran Bajo del Gualicho Formation (Miocene). This taxon was described from isolatedteeth and periotics, which has contributed to the taxonomic uncertainty of this species.Here we re-describe the referred materials to P. gualichensis, revise its taxonomic status,and evaluate the phylogenetic signal of Physeteroidea ear bones. Our results show that insperm whales the tympano-periotics morphology is poorly diagnostic at the species levels.Ontogenetic and intraspecific variation (including sexual dimorphism) and/or taphonomicprocesses could contribute to the minor differences observed. Based on the lack ofdiagnostic characters in both teeth and periotics, we consider P. gualichensis as nomendubium and re-identify it as Physeteroidea indet. We suggest that tympano-periotics ofsperm whales retain many plesiomorphies and a conservative morphology as a result of themorpho-functional constraints imposed by a highly specialized echolocation system.