Uria aalge (Pontoppidan 1763; 45cm tall) is the extant common murre or common guillemot or thin-billed murre. It is a strong flyer, both in the air and underwater. Basal to penguins, and derived from Megaceryle and Thalasseus, Uria also has an elongate sternum, two more dorsal vertebrae + ribs, and short wings.

Not related to Uria lomvia, which nests basal to auks. This genus was named later and so needs a new generic name.

Waimanu mannerigni (Slack et al. 2006, Mayr et al. 2018, Middle Paleocene, 62mya, 1m tall) is the oldest known penguin. Note the transitional radius and ulna. The scapula is shorter than the coracoid, unless only a partial scapula is preserved.

Sphensicus mendiculus (Sundevall 1871; 50cm tall) is the extant Galapagos penguin, the size of Uria, but swims like Aptenodytes. It prefers the cooler currents around the islands.

Aptenodytes forsteri (Miller 1778; 1.2m tall) the extant emperor penguin is considered a basal penguin, having split from the others about 40 mya. The large scapula anchored strong wing muscles for underwater flying. Note the C-shaped furcula and large patella.

Deguine, J-C 1974. Emperor Penguin: Bird of the Antarctic. The Stephen Greene Press, Vermont.

Hackett S et al. 2008. A phylogenetic study of birds reveals their evolutionary history. Science 320:1763–1768.

Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

Pontoppidan E 1763. Den Danske atlas eller Konge-Riget Dannemark, med dets naturlige egenskaber, elementer, indbyggere, værter, dyr og andre affødninger, dets gamle tildragelser og nærværende omstændingheder i alle provintzer, stæder, kirker, slotte og herre-gaarde. Forestillet ved en udførlig lands-beskrivelse, saa og oplyst med dertil forfærdigede land-kort over enhver provintz, samt ziret med stædernes prospecter, grund-ridser, og andre merkværdige kaabber-stykker. Efter Søy-kongelig allernaadigst befalning. 1: 1-723.

Slack KE et al. 2006. Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution. Molecular Biology and Evolution. 23 (6): 1144–1155.

Sundevall JE 1871. On birds from the Galapagos Islands. Proceedings of the Zoological Society of London 1871: 124–129.

wiki/Aptenodytes
wiki/Uria
wiki/Common_murre
wiki/Galapagos_penguin
wiki/Waimanu