A giant Oligocene fossil penguin from the North Island of New Zealand

ABSTRACT

Penguins (Sphenisciformes) have arguably the most complete and continuous fossil record of any avian clade, offering an ever-improving understanding of penguin phylogeny, biogeography, and the evolution of wing-propelled diving. Yet, our knowledge of the precise body proportions of stem-group penguins remains poor due to a dearth of articulated specimens. Here, we describe Kairuku waewaeroa sp. nov., a new giant penguin species from the Glen Massey Formation (Whaingaroan stage, 34.6–27.3 Ma). The holotype skeleton, discovered in Kawhia Harbour, North Island, New Zealand, is one of the most complete skeletons of a giant penguin yet uncovered. Our phylogenetic analysis recovers a clade uniting the New Zealand endemics Kairuku waewaeroa, Kairuku waitaki, and Kairuku grebneffi, which is supported by synapomorphies including a stout femoral shaft and tibiotarsi with a distinctly convex medial condyle. Kairuku waewaeroa is unique among stem penguins in having elongate tibiotarsi, revealing a new long-legged stem penguin body plan. The discovery of Kairuku waewaeroa contributes yet another penguin species to an Oligocene avifauna for Zealandia that is replete with giant birds.

ACKNOWLEDGMENTS

We thank C. Templer, M. Safey, and past and present members of the Hamilton Junior Naturalist Club for discovering, preparing, and donating the fossil. We thank S. Ghazally, P. Farquhar, S. Chappell, J. Primmer, R. Cook, S. Pennruscoe, A. Robertson, C. Meecham, and Waikato Museum Te Whare Taonga o Waikato for access to the fossil specimen and A. Tennyson, T. Schultz, and the Museum of New Zealand Te Papa Tongarewa, R. E. Fordyce and Otago University Geology Museum, and R. P. Scofield and Canterbury Museum, and K. Fleury and Otago Museum, for access to recent and fossil specimens. B. Hayward and Geomarine Research provided micropaleontology data. We thank the Willi Hennig Society for providing TNT as a free to use software for the cladistic analysis. We also thank associate editor V. De Pietri, technical editor J. Harris, G. Mayr and one anonymous reviewer for the useful comments on the manuscript.

AUTHOR CONTRIBUTIONS

DBT and DTK conceived the study. SG, DTK and DBT collected the data. SG conducted the majority of data analysis with input from DBT and DTK. SG, DBT and DTK wrote and edited the manuscript.

Additional information

Funding

SG was supported by a Massey University Doctoral Scholarship. DBT was supported by Massey University Strategic Innovation Fund (2014), Massey University School of Natural and Computational Sciences Minor Equipment Fund (2015), and Massey University Capital Equipment Fund (2019). DTK was supported by National Science Foundation award DEB1556615.