''Atocetus'' is an extinct genus of pontoporiid dolphin found in Miocene-age marine deposits in Peru and California.

Description

The type species, ''Atocetus iquensis'', is known from Serravallian-age strata of the Pisco Formation of Peru,De Muizon, 1988, p.131 while ''A. nasalis'' is known from Tortonian-age marine deposits of the

Modelo Formation The Modelo Formation is a Miocene geologic formation in the Simi Hills and western Santa Susana Mountains of southern California. It preserves fossils dating back to the Late Miocene of the Neogene period. See also * List of fossiliferous str ...

in California. Barnes (1985) originally described the latter as a species of '' Pithanodelphis'', but it was eventually transferred to ''Atocetus'' by Muizon (1988). The Miocene delphinidan ''"Champsodelphis" fuchsii'' from marine deposits in Austria was initially tentatively referred to ''Atocetus'' based on the discovery of partial skeletons from the Carpathian region with earbones similar to those of ''Atocetus'' but was eventually reassigned to '' Kentriodon'' following the discovery of additional earbones from Austria and Romania.

Phylogeny

Although ''Atocetus'' and other pithanodelphinines are usually assigned to Kentriodontidae, the cladistic analysis of Lambert et al. (2017) showed that ''Atocetus'' and ''Pithanodelphis'' form a clade with ''

Tagicetus ''Tagicetus'' is an extinct genus of dolphin belonging to the polyphyletic family Kentriodontidae. Although classified in the subfamily Kentriodontinae by Lambert et al. (2005), recent cladistic analysis places it as closer to extant delphinoids ...

'' and '' Lophocetus'' that is not only phylogenetically more derived than other kentriodontids but is also phylogenetically intermediate between the

baiji The baiji (; IPA: ; ''Lipotes vexillifer'', ''Lipotes'' meaning "left behind" and ''vexillifer'' "flag bearer") is a possibly extinct species of freshwater dolphin native to the Yangtze river system in China. It is thought to be the first dolph ...

and members of Inioidea and Phocoenidae. However, a subsequent cladistic analysis by Post et al. (2017) recovers ''Atocetus'' as a member of Pontoporiidae, which includes the franciscana.Post K, Louwye S, Lambert O. (2017) Scaldiporia vandokkumi, a new pontoporiid (Mammalia, Cetacea, Odontoceti) from the Late Miocene to earliest Pliocene of the Westerschelde estuary (The Netherlands) PeerJ 5:e3991 https://doi.org/10.7717/peerj.3991

References

Bibliography

* Kentriodontidae Prehistoric cetacean genera Serravallian life Tortonian life Miocene mammals of North America Neogene California Paleontology in California Fossils of the United States Miocene mammals of South America Laventan Neogene Peru Fossils of Peru Pisco Formation Fossil taxa described in 1988 {{paleo-whale-stub