''Platyosphys'' is a genus of

basilosaurid Basilosauridae is a family of extinct cetaceans. They lived during the middle to the early late Eocene and are known from all continents, including Antarctica. They were probably the first fully aquatic cetaceans.Buono M, Fordyce R.E., Marx F.G. ...

from Middle Eocene (

Bartonian The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic definitio ...

) of the eastern United States and

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

Taxonomy

The type species, ''Platyosphys paulsoni'', was originally described as '' Zeuglodon paulsoni'' in 1873 on the basis of several vertebrae from a Bartonian-age horizon in southern Ukraine. In his 1936 monograph regarding

Archaeoceti Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene (). Representing the earliest cetacean radiation, they include the initia ...

Remington Kellogg Arthur Remington Kellogg (5 October 1892 – 8 May 1969) was an American naturalist and a director of the United States National Museum. His work focused on marine mammals. Early life and career Kellogg was born in Davenport, Iowa, and quick ...

recognized the distinct nature of the taxon and coined the new genus ''Platyosphys'' for ''Z. paulsoni''. Another new species of ''Platyosphys'', ''P. einori'', was coined for vertebrae, a scapula, and rib fragments in 2001. In the original description of ''

Basilotritus ''Basilotritus'' is a genus of basilosaurid early whale known from the early late Middle Eocene (late Lutetian to Bartonian, ) Kiev Formation of the Ukraine, Stockletten Formation of Germany, Tongeren Formation of the Netherlands, Giushi F ...

'', ''Platyosphys'' and its constituent species were considered ''nomina dubia'' because their material was considered insufficiently diagnostic to generic or specific level. However, a 2015 paper describing archaeocetes from the Western Sahara described a new species, ''P. aithai'', and reiterated the diagnostic nature of the type species of ''Platyosphys'', suggesting that ''Basilotritus'' might be a synonym of ''Platyosphys''. ''Platosphys aithai'' was renamed '' Antaecetus'' by Gingerich et al. (2022), who also made ''Pachycetus robustus'' a junior synonym of ''paulsonii'' along with ''Platyosphys einori'' to create the new combination ''Pachycetus paulsonii'', making ''paulsonii'' the epithet of the ''Pachycetus'' type species. Gingerich PD, Amane A, Zouhri S (2022) Skull and partial skeleton of a new pachycetine genus (Cetacea, Basilosauridae) from the Aridal Formation, Bartonian middle Eocene, of southwestern Morocco. PLoS ONE 17(10): e0276110. doi:10.1371/journal.pone.0276110

References

Basilosauridae Fossil taxa described in 1936 Prehistoric cetacean genera Eocene mammals of Europe Eocene mammals of North America {{paleo-whale-stub