Master’s Defense – Margot D. Nelson

Candidate: Margot D. Nelson

Master of Science in Earth Systems Sciences 

Department of Geography and Geoinformation Science


Date:   Tuesday, April 17th, 2019

Time:   10:30 AM – 12:00 PM

Place:  Exploratory Hall 3301


TITLE: A new Platanistoidea (Cetacea, Odontoceti) from the Nye Formation of Oregon


Thesis Director: Dr. Mark Uhen

Committee Members: Dr. Stacey Verardo and Dr. Geoff Gilleaudeau


This thesis describes an early odontocete, gen. et. sp. nov., from the latest Oligocene-earliest Miocene Nye Formation in Oregon. I assign it to the Platanistoidea, a large superfamily of odontocetes whose sole surviving member is Platanista gangetica, the Ganges river dolphin. Despite the diversity of the Platanistoidea, it remains poorly understood and in need of revision. As one of the earliest-diverging clade of crown odontocetes, understanding their distribution, morphology, and phylogeny is crucial to understanding the radiation of archaic odontocetes in the late Oligocene to the middle Miocene. N. gen n. sp., represented by the holotype USNM 335224, possesses several synapomorphies of the Platanistoidea; however, similarity between n. gen n. sp. and other archaic odontocetes suggests that these early odontocetes may be closer to the Platanistoidea than initially thought, especially those in the “Chilcacetus clade”. The specimen’s probable location in the lower Nye Formation suggests that n. gen n. sp. one of the older platanistoids known in the fossil record.