Great Auk - Taxonomy and Evolution

Taxonomy and Evolution

Analysis of mtDNA sequences has confirmed morphological and biogeographical studies suggesting that the Razorbill is the Great Auk's closest living relative. The Great Auk was also closely related to the Little Auk (Dovekie), which underwent a radically different evolution compared to Pinguinus. Due to its outward similarity to the Razorbill (apart from flightlessness and size), the Great Auk was often placed in the genus Alca, following Linnaeus.

The fossil record (especially the sister species Pinguinus alfrednewtoni) and molecular evidence show that the three genera, while closely related, diverged soon after their common ancestor, a bird probably similar to a stout Xantus's Murrelet, had spread to the coasts of the Atlantic. By that time the murres, or Atlantic guillemots, had apparently already split from the other Atlantic alcids. Razorbill-like birds were common in the Atlantic during the Pliocene, but the evolution of the Little Auk is sparsely documented. The molecular data are compatible with either view, but the weight of evidence suggests placing the Great Auk in a distinct genus. Some ornithologists still feel it is more appropriate to retain the species in the genus Alca, however. The Great Auk was not closely related to the other extinct genera of flightless alcids, Mancalla, Praemancalla, and Alcodes.

Pinguinus alfrednewtoni was a larger and also flightless member of the genus Pinguinus that lived during the Early Pliocene. Known from bones found in the Yorktown Formation of the Lee Creek Mine in North Carolina, it is believed to have split along with the Great Auk from a common ancestor. Pinguinus alfrednewtoni lived in the western Atlantic while the Great Auk lived in the eastern Atlantic, but after the former died out after the Pliocene, the Great Auk replaced it.