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. (28th August 2015)

• Record Type: Journal Article
• Authors: Boessenecker, Robert W.; Fordyce, R. Ewan
• Is Part Of: Zoological journal of the Linnean Society. Volume 175:Number 3(2015:Nov.)
• Page Start: 607
• Page End: 660
• Publication Date: 2015-08-28
• Subjects: Zoology -- Periodicals; 590
• DOI: 10.1111/zoj.12297
• Languages: English
• ISSNs: 0024-4082

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>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 '<italic>M</italic><italic>auicetus</italic>' <italic>lophocephalus</italic> (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 '<italic>M</italic><italic>auicetus</italic>' <italic>lophocephalus</italic>, and indicating that this species may have retained adult teeth. <bold><italic>T</italic></bold><bold><italic>okarahia kauaeroa</italic> gen. et sp. nov.</bold> 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 (> 25.2 Mya). '<italic>M</italic><italic>auicetus</italic>' <italic>lophocephalus</italic> is relatively similar and recombined as <italic>T</italic><italic>okarahia lophocephalus</italic>. Phylogenetic analysis supports the inclusion of <italic>T</italic><italic>okarahia</italic> within the Eomysticetidae, alongside <italic>E</italic><italic>omysticetus</italic>, <italic>M</italic><italic>icromysticetus</italic>, <italic>Y</italic><italic>amatocetus</italic>, and <italic>T</italic><italic>ohoraata</italic>, and strongly supports the monophyly of Eomysticetidae. <italic>T</italic><italic>okarahia</italic> lacked extreme rostral kinesis of extant Mysticeti, and primitively retained a delicate archaeocete‐like posterior mandible and synovial temporomandibular joint, suggesting that <italic>T</italic><italic>okarahia</italic> was capable of, at most, limited lunge feeding in contrast to extant Balaenopteridae, and used an alternative as‐yet unspecified feeding strategy. © 2015 The Linnean Society of London</p> </abstract>