155 D15. Paleontology II

Wednesday, 28 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

WAIMA FORMATION FOSSIL: A POSSIBLE AQUATINIAN CETACEAN

Paper number: 155-13
Program: Technical Sessions
Time: 7:50 PM – 8:00 PM

Authors

Abstract

The Early Miocene epoch is a pivotal period of radiation in cetaceans, and yet is one of the least understood, primarily due to a gap in the Odontoceti or “toothed whale” fossil record. The current number of Odontocete families identified is misleading as they are represented by a single sample in most cases. In 2016 a series of earthquakes uplifted the Kaikoura coastline of New Zealand, exposing previously submerged rock units and unidentified fossils. On January 16, 2019 unidentified megafauna fossils were extracted from the Early to Middle Miocene Waima Formation in South Bay, Kaikoura Peninsula. Previously extracted megafauna fossils have been identified within the Waima Formation, with those of Seal Point (ZMT 73), Kaikoura Peninsula, determined to be Odontocete in origin. The purpose of this study was to extract and identify the unidentified fossil and to correlate with ZMT 73. Laboratory extraction of fossil components was interrupted by an early departure from Aotearoa New Zealand due to Covid-19, leading to the completion of this task in lockdown with limited resources. Extraction and reassembly resulted in the identification of three partial ribs and one phalange. Two of the partial ribs include a tubercle and articular facet and were classified as proximal ends. The partial ribs met a taphonomic completeness of grade 1 (only vertebrae or ribs, <10 elements), which limits the extent to of identification, however, size limits species origin to one of five modern proxies. Morphological, comparative, and sedimentary analysis resulted in rejecting the original hypothesis as additional parts of ZMT 73, as the partial ribs are too large to come from a small Papahu-like Odontocete. Additional comparative analysis in conjunction with sedimentary analysis led to the hypothesis that the fossils are Odontocete in origin, and belong to a small whale (i.e. modern equivalent Globicephalus macrorhynchus, Grampus griseus) rather than a dolphin. It is recommended that the Waima Formation shore platform of the Kaikoura Peninsula be examined for further megafauna fossils, aiding in the understanding and origin of Odontocete in the early Miocene.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-359481

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