Temporal range: Pliocene to recent
Miller, JF, 1778
- King penguin, Aptenodytes patagonicus
- Aptenodytes patagonicus patagonicus
- Aptenodytes patagonicus halli
- Emperor penguin, Aptenodytes forsteri
- Ridgen's penguin (Aptenodytes ridgeni) is an extinct species known from fossil bones of Early or Late Pliocene age.
Combined morphological and molecular data  have shown the genus Aptenodytes to be basal to all other living penguins, that is, the genus split off from a branch which led to all other species. DNA evidence suggests this split occurred around 40 million years ago. This had been foreshadowed by an attempt to classify penguins by their behaviour, which also predicted the genus' basal nature.
Two monotypic species extant:
|Common and binomial names||Image||Description||Range|
|122 cm (4 ft) tall, weighing 22–37 kg (48.5–82 lb), the adult has deep black dorsal feathers, covering the head, chin, throat, back, dorsal part of the flippers, and tail. The underparts of the wings and belly are white, becoming pale yellow in the upper breast, ear patches are bright yellow. The upper mandible is black, and the lower mandible can be pink, orange or lilac. Males and females are similar in size and colouration.||Circumpolar distribution in the Antarctic between the 66° and 77° S. It almost always breeds on stable pack ice near the coast and up to 18 km (11 mi) offshore.|
|90 cm (3 ft) tall, weighing 11 to 16 kg (24 to 35 lb), The upperparts are steel blue-grey, darkening to black on the head, the belly is white fading to orange on the upper breast with bright orange ear patches. The black bill is long and slender. The lower mandible bears a striking pink or orange-coloured mandibular plate||Breeds on the subantarctic islands between 45° and 55° S at the northern reaches of Antarctica, as well as Tierra del Fuego, the Falkland Islands, and other temperate islands of the region.|
- DeNapoli, Dyan (2010). The Great Penguin Rescue. New York, NY: Simon & Schuster. p. 283. ISBN 978-1-4391-4817-4.
- Ksepka, D. T. B.; Sara Giannini; Norberto P. (2006). "The phylogeny of the living and fossil Sphenisciformes (penguins)". Cladistics. 22 (5): 412–441. doi:10.1111/j.1096-0031.2006.00116.x.
- Baker AJ, Pereira SL, Haddrath OP, Edge KA (2006). "Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling". Proc Biol Sci. 273 (1582): 11–17. doi:10.1098/rspb.2005.3260. PMC 1560011. PMID 16519228.
- Jouventin P (1982). "Visual and vocal signals in penguins, their evolution and adaptive characters". Adv. Ethol. 24: 1–149.
- "Zoological Nomenclature Resource: Ciconiiformes (Version 9.004)". www.zoonomen.net. 2008-07-05.
- University of Michigan Museum of Zoology. "Aptenodytes forsteri". Archived from the original on 23 December 2007. Retrieved 2008-01-01.
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