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

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; 55.5–59.5Ma) Moeraki Formation of the South Island, New Zealand. The largest specimen is assigned to a new species, Kumimanu fordycei sp. nov., that may have been the largest penguin ever to have lived. Allometric regressions based on humerus length and humerus head width of extant penguins yield mean estimates of a live body mass in the range of 159.4 kg (95% CI: 143.4 kg–179.6kg) and 148.7 kg (95% CI: 143.4kg–180.0kg), respectively, for Kumimanu fordycei. A second new species, Petradyptes stonehousei gen. et sp. nov., is represented by five specimens and was slightly larger than the extant emperor penguin Aptenodytes forsteri. Two small humeri represent an additional smaller unnamed penguin species. Parsimony and Bayesian phylogenetic an..., ,