Largest-known fossil penguin provides insight into the early evolution of sphenisciform body size and flipper anatomy

• Main Authors: Ksepka, DT, Field, DJ, Heath, TA, Pett, W, Thomas, DB, Giovanardi, S, Tennyson, AJD
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2022
• Subjects: 31 Biological Sciences; 3103 Ecology; 3104 Evolutionary Biology; 37 Earth Sciences; 3705 Geology; New Zealand; Aptenodytes forsteri
• Online Access: https://www.repository.cam.ac.uk/handle/1810/341076; https://doi.org/10.17863/CAM.88503

<jats:title>Abstract</jats:title><jats:p>Recent fossil discoveries from New Zealand have revealed a remarkably diverse assemblage of Paleocene stem group penguins. Here, we add to this growing record by describing nine new penguin specimens from the late Paleocene (upper Teurian local stage; 55.5–59.5 Ma) Moeraki Formation of the South Island, New Zealand. The largest specimen is assigned to a new species, <jats:italic>Kumimanu fordycei</jats:italic> n. sp., which may have been the largest penguin ever to have lived. Allometric regressions based on humerus length and humerus proximal width of extant penguins yield mean estimates of a live body mass in the range of 148.0 kg (95% CI: 132.5 kg–165.3 kg) and 159.7 kg (95% CI: 142.6 kg–178.8 kg), respectively, for <jats:italic>Kumimanu fordycei</jats:italic>. A second new species, <jats:italic>Petradyptes stonehousei</jats:italic> n. gen. n. sp., is represented by five specimens and was slightly larger than the extant emperor penguin <jats:italic>Aptenodytes forsteri</jats:italic>. Two small humeri represent an additional smaller unnamed penguin species. Parsimony and Bayesian phylogenetic analyses recover <jats:italic>Kumimanu</jats:italic> and <jats:italic>Petradyptes</jats:italic> crownward of the early Paleocene mainland NZ taxa <jats:italic>Waimanu</jats:italic> and <jats:italic>Muriwaimanu</jats:italic>, but stemward of the Chatham Island taxon <jats:italic>Kupoupou</jats:italic>. These analyses differ, however, in the placement of these two taxa relative to <jats:italic>Sequiwaimanu</jats:italic>, <jats:italic>Crossvallia</jats:italic>, and <jats:italic>Kaiika</jats:italic>. The massive size and placement of <jats:italic>Kumimanu fordycei</jats:italic> close to the root of the penguin tree provide additional support for a scenario in which penguins reached the upper limit of sphenisciform ...