Heaviest species of penguin ever

The heaviest species of penguin ever recorded is a newly described prehistoric species, Kumimanu fordycei, known from fossil remains discovered inside boulders in North Otago, on New Zealand's South Island. By comparing the size and density of its bones with those of modern-day penguins, researchers estimate that it weighed 154 kg (340 lb), which is three times that of today's largest species, the emperor penguin (Aptenodytes forsteri). The rocks containing the remains of this new giant fossil species date between 55.5 million years and 59.5 million years old, meaning that it existed during the Late Palaeocene. Details of the record-breaking prehistoric penguin were published in the Journal of Paleontology on 8 February 2023.

The height of K. fordycei is debated, though a related extinct species, K. biceae, has been estimated to have stood up to 1.77 m (5 ft). A lack of complete skeletons of extinct giant penguins found to date makes it difficult for height to be determined with any degree of certainty.

Prior to the recent discovery and description of K. fordycei, the largest species of penguin known to science was the colossus penguin (Palaeeudyptes klekowskii), which is estimated to have weighed as much as 115 kg (253 lb 8 oz), and stood up to 2 m (6 ft 6 in) tall. It lived in Antarctica's Seymour Island approximately 37 million years ago, during the Late Eocene, and is represented by the most complete fossil remains ever found for a penguin species in Antarctica.