Cosmopolitanism and Miocene survival of Eomysticetidae (Cetacea: Mysticeti) revealed by new fossils from New Zealand

The Eomysticetidae is an extinct family of early-diverging baleen whales. They are baleen-bearing filter feeders, but some have vestigial teeth. A limited fossil record indicates an acme during the Oligocene and probable worldwide distribution (South Carolina, USA, Japan, New Zealand), but little further regarding distribution and the timing of their origin and extinction. Newly discovered Oligo-Miocene specimens from New Zealand elucidate the biochronology and biogeography of the Eomysticetidae. First, a new specimen of the eomysticetid Waharoa from the upper Otekaike Limestone represents the youngest reliably dated eomysticetid worldwide (upper Waitakian, earliest Miocene). The fossil demonstrates that eomysticetids survived into the earliest Miocene. Second, a specimen from the lower Otekaike Limestone (Duntroonian, late Oligocene) shares unique craniomandibular features with the eomysticetid Yamatocetus, a genus hitherto reported only from Japan, indicating cosmopolitan or antitropical distribution for eomysticetids. Incomplete specimens such as these may elucidate biogeography, faunal change and other aspects of cetacean paleobiology.