Palaeeudyptes antarcticus, also referred to as the narrow-flippered penguin, is the type species of the extinct penguin genus Palaeeudyptes. It was a huge species, albeit probably with a large size variation. Although the size range can only be loosely estimated, the birds seem to have stood between 43 to 55 inches high in life (i.e. somewhat larger than an emperor penguin), placing this species and its congener Palaeeudyptes marplesi among the largest penguin species known. It was the last known Palaeeudyptes species, and although the exact time when it lived is not precisely determined, it may have evolved from P. marplesi, or they might even have been a single species which slightly decreased in size over time.