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.

摘要

企鹅（Sphenisciformes）可以说是所有鸟类进化枝中最完整和最连续的化石记录，提供了对企鹅系统发育、生物地理学和翼驱动潜水进化的不断改进的理解。然而，由于缺乏关节标本，我们对茎群企鹅的精确身体比例的了解仍然很少。在这里，我们描述了Kairuku waewaeroa sp。11 月，来自 Glen Massey 组（Whaingaroan 阶段，34.6-27.3 Ma）的新巨型企鹅物种。在新西兰北岛 Kawhia Harbour 发现的正模骨架是迄今发现的最完整的巨型企鹅骨架之一。我们的系统发育分析恢复了一个将新西兰特有物种Kairuku waewaeroa、Kairuku waitaki和Kairuku grebneffi，它由突触支持，包括粗壮的股骨干和胫骨与明显凸出的内侧髁。Kairuku waewaeroa在茎企鹅中是独一无二的，它具有细长的胫骨，揭示了一种新的长腿茎企鹅的身体结构。Kairuku waewaeroa的发现为西兰岛的渐新世鸟类群提供了另一种企鹅物种，该物种充满了巨型鸟类。