A new Eomysticetid (Mammalia: Cetacea) from the Late Oligocene of New Zealand and a re‐evaluation of ‘Mauicetus’ waitakiensis

The published O ligocene record of mysticetes (baleen whales) is dominated by toothed mysticetes in addition to the Eomysticetidae, the earliest known chaeomysticetes known only from the O ligocene. Formally recognized eomysticetids include examples from the O ligocene of S outh C arolina, USA ( E omysticetus ), and J apan ( Y amatocetus ). A new fossil from the upper O ligocene O tekaike L imestone including a partial skull, periotic, tympanic bulla, mandible and some postcrania is here described as T ohoraata raekohao gen. et sp. nov. T ohoraata confirms the presence of an eomysticetid in N ew Z ealand. T ohoraata raekohao is characterized by delicate frontal with numerous supraorbital foramina and sulci, relatively long exposure of the frontal and parietal along a transversely narrow intertemporal region, greatly enlarged temporal fossa, massive and anteriorly directed zygomatic process lacking a supramastoid crest, and a periotic with superior process reduced to a low ridge with anterior and posterior apices. Cranial and postcranial fusion of elements, development 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 exoccipital, permit referral of the fragmentary ‘ M auicetus’ waitakiensis of M arples into the genus T ohoraata , resulting in T ohoraata waitakiensis comb. nov. Description of T . raekohao and resolution of the relationships of the hitherto problematic T ohoraata waitakiensis indicates that several eomysticetids were present in the S outhern O cean during the L ate O ligocene.