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Abstract
Eomysticetids represent a worldwide, short-lived radiation of archaic baleen-bearing mysticetes that elucidate morphofunctional shifts and ontogenetic change amongst early Neoceti. Fossils of eomysticetids are now recorded from Oligocene marine rocks along the margins of the North Pacific (Japan), North Atlantic (South Carolina), and the Southern Ocean (New Zealand). The assemblage from New Zealand is diverse, with five species in three genera present during the Duntroonian stage (Chattian, 27.3–25.2 Ma). A new genus and species of eomysticetid from the lower Kokoamu Greensand of New Zealand, Matapa waihao gen. et sp. nov., increases the known diversity of Southern Hemisphere eomysticetids. Matapa uniquely exhibits a rounded margin of the occipital shield, and shares a mosaic of features seen in Northern Hemisphere eomysticetids such as a large squamosal prominence, an inflated and posteriorly rounded paroccipital process, and a double-faced posterior bullar facet with longitudinal ridges. The holotype specimen of Matapa waihao is ontogenetically immature, but ontogenetically static tympanoperiotic characters that diagnose this new species are shared by referred adult specimens. Matapa is uppermost Whaingaroan (28.1–27.3 Ma) in age, the oldest eomysticetid from New Zealand. Fossils of Matapa are recovered from both the modern west and east coast of New Zealand which, during the Oligocene, were on the margin of the Southern Ocean. Inclusion of Matapa within an earlier published cladistic analysis recovers Matapa as the earliest diverging member of the New Zealand eomysticetid clade, and confirms eomysticetid monophyly. The taxonomy, morphology and geochronological age of all known eomysticetids are reviewed.
http://zoobank.org/urn:lsid:zoobank.org:pub:EE1CB5CC-618B-4ABA-9D97-5B9DEDD3470E
Acknowledgements
We thank J. A. Grant-Mackie (University of Auckland), for facilitating loans of eomysticetid specimens, and R. Cotton, J. A. Grant-Mackie, A. Grebneff, C. M. Jones, L. T. Kerr and J. G. Williams for collecting and excavating Matapa specimens (AUGD and OU) in the field. Thanks to D. Hulston for granting locality access, and thanks to P. Wood for guiding REF through Te Tahi Cave. Preparation was carefully undertaken by L. T. Kerr, who graciously volunteered many hours, and was finished by D. M. Nyhof, S. White and RWB. This study benefited from numerous discussions on cetacean evolution and morphology, stratigraphy and taphonomy with G. Aguirre-Fernandez, A. Berta, M. Churchill, J. Corrie, E. Ekdale, J. El Adli, E. M. G. Fitzgerald, J. H. Geisler, J. A. Grant-Mackie, N. de B. Hornibrook, N. Hudson, H. Ichishima, F. G. Marx, A. E. Sanders, Y. Tanaka and C. H. Tsai. Thanks to D. J. Bohaska, L. G. Barnes, M. Brown, T. A. Deméré, M. Goodwin, P. Holroyd, S. A. McLeod, C. W. Potter, N. D. Pyenson, V. Rhue, A. E. Sanders, A. Stewart and A. Tennyson for facilitating access to fossil and modern cetaceans under their care. Discussions of Māori nomenclature and name construction with S. White and with R. Donaldson on behalf of the Runanga o Waihao were most instructive. Thanks to T. Reichgelt for assistance with the New Zealand Fossil Record Database. F. G. Marx provided photographs of fossil and modern mysticetes we were unable study directly. An earlier draft of this study benefited from comments by E. M. G. Fitzgerald, M. D. Gottfried and O. Hampe. This study was funded by a University of Otago Doctoral Scholarship to RWB. Field collection and laboratory preparation was supported by grants to REF from the University of Otago Research Committee and the former New Zealand University Grants Committee, and the Geology (University of Otago) Head of Department and PBRF funds.
Supplemental material
Supplemental material is available online DOI: http://dx.doi.org/10.1080/14772019.2016.1191045
