Miocene sea cow (Sirenia) from Papua New Guinea sheds light on sirenian evolution in the Indo-Pacific

ABSTRACT

A partial postcranial skeleton (vertebrae and ribs) of an indeterminate sirenian is described from Selminum Tem cave in the Hindenburg Range, Western Province of Papua New Guinea. It was derived from a section of the Darai Limestone dating to the Burdigalian–Serravallian (early–middle Miocene) and representing shallow platform carbonates. The thoracic vertebrae are remarkably small, being comparable in size to the vertebrae of Nanosiren garciae and implying small body size, although it is uncertain whether the specimen represents a diminutive adult or juvenile individual. These fossils represent the geologically earliest mammal recorded from the island of New Guinea and the earliest evidence of Sirenia in Australasia. Thus, this fossil evidence provides a minimum date (∼11.8 Ma) for the earliest presence of sirenians in Australasian coastal marine ecosystems, as well as their primary food source, seagrasses.

ACKNOWLEDGMENTS

We thank M.-A. Binnie (South Australian Museum), D. Bohaska (National Museum of Natural History), and G. Mosuwadoga (National Museum and Art Gallery of Papua New Guinea) for access to collections; and two referees for comments on the manuscript. This work was initiated during a Smithsonian Postdoctoral Fellowship awarded to E.M.G.F., and continued with support from the Harold Mitchell Foundation and Museum Victoria. E.M.G.F. thanks the South Australian Museum for facilitating research on its collections. J.V.G.'s contribution was partially supported by WBHR Louis Stokes Alliance for Minority Participation Bridge to the Doctorate Program at Howard University; a predoctoral fellowship from the National Museum of Natural History; and NSF Earth Sciences grant 0929117 awarded to Daryl P. Domning.

Handling editor: Anjali Goswami.