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

Abstract 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 the late (upper Teurian local stage; 55.5–59.5 Ma) Moeraki Formation South Island, Zealand. The largest specimen is assigned species, Kumimanu fordycei n. sp., which may been ever lived. Allometric regressions based on humerus length and proximal width extant penguins yield mean estimates live body mass in range 148.0 kg (95% CI: 132.5 kg–165.3 kg) 159.7 142.6 kg–178.8 kg), respectively, for . A second Petradyptes stonehousei gen. represented five was slightly larger than emperor Aptenodytes forsteri Two small humeri represent an additional smaller unnamed species. Parsimony Bayesian phylogenetic analyses recover crownward early mainland NZ taxa Waimanu Muriwaimanu , but stemward Chatham Island taxon Kupoupou These differ, however, placement these two relative Sequiwaimanu Crossvallia Kaiika massive size close root tree provide support scenario reached upper limit sphenisciform very their evolutionary history, while still retaining numerous plesiomorphic features flipper. UUID: https://zoobank.org/15b1d5b2-a5a0-4aa5-ba0a-8ef3b8461730