A new, allodelphinid-like dolphin from New Zealand Otekaike Limestone (Waitakian Stage, Oligocene-Miocene boundary)

Burt, Alexandra

Between 36-30 Ma, the initial radiation of odontocetes and mysticetes led to an array of new, specialized toothed whales. The odontocete superfamily Platanistoidea, reached peak diversity between the Oligocene and Miocene. Allodelphinidae is one of the most basal families in Platanistoidea. Small craniums, long rostrums and three to five meter body lengths characterize allodelphinids in the fossil record. Currently, allodelphinids have been reported from Oligocene to early- to mid-Miocene settings in Japan and the United States west coast, but never in the Southern Hemisphere. A new odontocete (OU22773) is reported from the late Oligocene-early Miocene (Waitakian Stage) Otekaike Limestone in Hakataramea Quarry, South Canterbury, New Zealand. The cranium of the dolphin is small and features a broad, flattened facial region with directional asymmetry. Additionally, the presence of two, unfused vertebral epiphysis plates and a small tusk-like tooth with an opening to the pulp cavity suggest OU22773 was young. In phylogenetic analysis of skull, tympanic bullae, and scapula characters of nine odontocete taxa, the resulting consensus tree suggests a close relationship between OU22773 and Allodelphis from the northeast Pacific. As an entirely new specimen for New Zealand, OU22773 will provide additional detail for current understanding of evolutionary relationships between platanistoids and other odontocetes.

33 pages, US letter

2016Burt