A NEW EOMYSTICETID (MAMMALIA: CETACEA) FROM THE LATE OLIGOCENE OF NEW ZEALAND AND A RE-EVALUATION OF ‘ MAUICETUS ’ WAITAKIENSIS ROBERT W. BOESSENECKER 1,2 and R. EWAN FORDYCE 1 1 Department of Geology, University of Otago, 360 Leith Walk, PO Box 56, Dunedin, 9010, New Zealand; e-mails: robert.boessenecker@otago.ac.nz, ewan.fordyce@otago.ac.nz 2 University of California Museum of Paleontology, Berkeley, 94720, CA USA Typescript received 19 May 2014; accepted in revised form 3 July 2014 Abstract: The published Oligocene record of mysticetes (baleen whales) is dominated by toothed mysticetes in addi- tion to the Eomysticetidae, the earliest known chaeomysticetes known only from the Oligocene. Formally recognized eomys- ticetids include examples from the Oligocene of South Caroli- na, USA (Eomysticetus), and Japan (Yamatocetus). A new fossil from the upper Oligocene Otekaike Limestone including a partial skull, periotic, tympanic bulla, mandible and some postcrania is here described as Tohoraata raekohao gen. et sp. nov. Tohoraata confirms the presence of an eomysticetid in New Zealand. Tohoraata raekohao is characterized by delicate frontal with numerous supraorbital foramina and sulci, rela- tively long exposure of the frontal and parietal along a trans- versely narrow intertemporal region, greatly enlarged temporal fossa, massive and anteriorly directed zygomatic process lacking a supramastoid crest, and a periotic with supe- rior process reduced to a low ridge with anterior and posterior apices. Cranial and postcranial fusion of elements, develop- ment of muscle attachments and osteohistology demonstrate that the T. raekohao holotype is an adult or possible subadult. Features of the tympanic bulla including a relatively wide bulla with a medial lobe that is transversely much wider than the lateral lobe, and a slightly posterolaterally facing exoccipi- tal, permit referral of the fragmentary ‘Mauicetus’ waitakiensis of Marples into the genus Tohoraata, resulting in Tohoraata waitakiensis comb. nov. Description of T. raekohao and reso- lution of the relationships of the hitherto problematic Tohora- ata waitakiensis indicates that several eomysticetids were present in the Southern Ocean during the Late Oligocene. Key words: Eomysticetidae, Mysticeti, Cetacea, Oligocene, New Zealand. T HE global Neogene record of baleen whales (Cetacea: Mysticeti) is rich and has been the focus of intense study since the later part of the nineteenth century (Fordyce and Muizon 2001). The published record is predominantly rep- resented by fossils from Europe, North America and Japan (Fordyce and Barnes 1994; Fordyce and Muizon 2001). The published Oligocene record of mysticetes, on the other hand, is sparse and represented by several toothed mystice- tes from the margins of the Pacific (Barnes et al. 1995; Fitzgerald 2004, 2006, 2010, 2012) and some fragmentary toothless mysticetes from South Carolina, Austria, Japan and New Zealand (Benham 1937; Marples 1956; Sanders and Barnes 2002a, b; Rothausen 1971; Okazaki 2012). Oligocene marine rocks in the South Island, New Zea- land, have produced a rich fossil record of marine verte- brates, including sharks (Chapman 1918; Keyes 1982, 1984; Gottfried and Fordyce 2001), bony fish (Gottfried et al. 2006, 2012), penguins (Marples 1952; Simpson 1971; Ksepka et al. 2012), archaeocetes (Hector 1881; Fordyce 2004), dolphins (Dickson 1964; Fordyce 1994) and baleen whales (Benham 1937, 1942; Marples 1956; Keyes 1973; Fordyce 1980, 1991, 2002, 2005, 2006; Boessenecker and Fordyce 2013a, b). In a series of papers beginning in the 1930s, Benham (1937, 1942) described several fragmentary fossil mysticete specimens from the Oligocene Kokoamu Greensand, Otekaike Limestone and Oligocene – earliest Miocene Milburn Limestone. These formations span the local upper Whaingaroan, Duntroonian and Waitakian stages, basal Chattian to basal Aquitanian. One of these, Mauicetus parki, is now thought to be an edentulous stem balaenopteroid (Fordyce 2005; Steeman 2007). Subse- quently, Marples (1956) described three new species from the Duntroonian Kokoamu Greensand and Duntroonian– Waitakian Otekaike Limestone which he placed within Mauicetus: Mauicetus brevicollis (Otekaike Limestone), Mauicetus lophocephalus (Kokoamu Greensand) and © The Palaeontological Association doi: 10.1002/spp2.1005 1 [Papers in Palaeontology, 2014, pp. 1–34]