A new genus and species of eomysticetid ( C etacea: M ysticeti) and a reinterpretation of ‘ M auicetus ’ lophocephalus M arples, 1956: Transitional baleen whales from the upper O ligocene of N ew Z ealand

The early evolution of toothless baleen whales ( C haeomysticeti) remains elusive, despite a robust record of E ocene– O ligocene archaeocetes and toothed mysticetes. Eomysticetids, a group of archaic longirostrine and putatively toothless baleen whales, fill in a crucial morphological gap between well‐known toothed mysticetes and more crownward N eogene M ysticeti. A historically important but perplexing cetacean is ‘ M auicetus ’ lophocephalus (upper O ligocene S outh I sland, N ew Z ealand). The discovery of new skulls and skeletons of eomysticetids from the O ligocene K okoamu G reensand and O tekaike L imestone permit a redescription and modern reinterpretation of ‘ M auicetus ’ lophocephalus , and indicating that this species may have retained adult teeth. Tokarahia kauaeroa  gen. et sp. nov. is erected on the basis of a well‐preserved subadult to adult skull with mandibles, tympanoperiotics, and cervical and thoracic vertebrae, ribs, sternum, and forelimbs from the O tekaike L imestone (> 25.2 Mya). ‘ M auicetus ’ lophocephalus is relatively similar and recombined as T okarahia lophocephalus . Phylogenetic analysis supports the inclusion of T okarahia within the E omysticetidae, alongside E omysticetus , M icromysticetus , Y amatocetus , and T ohoraata , and strongly supports the monophyly of E omysticetidae. T okarahia lacked extreme rostral kinesis of extant M ysticeti, and primitively retained a delicate archaeocete‐like posterior mandible and synovial temporomandibular joint, suggesting that T okarahia was capable of, at most, limited lunge feeding in contrast to extant B alaenopteridae, and used an alternative as‐yet unspecified feeding strategy. © 2015 The Linnean Society of London