A new genus and species of eomysticetid (Cetacea: Mysticeti) and a reinterpretation of "Mauicetus' lophocephalus Marples, 1956: Transitional baleen whales from the upper Oligocene of New Zealand

作者：Boessenecker Robert W^*; Fordyce R Ewan

来源：Zoological Journal of the Linnean Society, 2015, 175(3): 607-660.

DOI：10.1111/zoj.12297

• Baleen whales
• Oligocene
• cetacea
• Mysticeti
• Eomysticetidae

The early evolution of toothless baleen whales (Chaeomysticeti) remains elusive, despite a robust record of Eocene-Oligocene 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 Neogene Mysticeti. A historically important but perplexing cetacean is Mauicetus' lophocephalus (upper Oligocene South Island, New Zealand). The discovery of new skulls and skeletons of eomysticetids from the Oligocene Kokoamu Greensand and Otekaike Limestone permit a redescription and modern reinterpretation of Mauicetus' lophocephalus, and indicating that this species may have retained adult teeth. Tokarahia kauaeroagen.etsp.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 Otekaike Limestone (>25.2Mya). Mauicetus' lophocephalus is relatively similar and recombined as Tokarahia lophocephalus. Phylogenetic analysis supports the inclusion of Tokarahia within the Eomysticetidae, alongside Eomysticetus, Micromysticetus, Yamatocetus, and Tohoraata, and strongly supports the monophyly of Eomysticetidae. Tokarahia lacked extreme rostral kinesis of extant Mysticeti, and primitively retained a delicate archaeocete-like posterior mandible and synovial temporomandibular joint, suggesting that Tokarahia was capable of, at most, limited lunge feeding in contrast to extant Balaenopteridae, and used an alternative as-yet unspecified feeding strategy.

• 出版日期2015-11