Abstract
Although flightless alcids from the Miocene and Pliocene of the eastern Pacific Ocean have been known for over 100 years, there is no detailed evaluation of diversity and systematic placement of these taxa. This is the first combined analysis of morphological and molecular data to include all extant alcids, the recently extinct Great Auk Pinguinus impennis, the mancalline auks, and a large outgroup sampling of 29 additional non-alcid charadriiforms. Based on the systematic placement of Mancallinae outside of crown clade Alcidae, the clade name Pan-Alcidae is proposed to include all known alcids. An extensive review of the Mancallinae fossil record resulted in taxonomic revision of the clade, and identification of three new species. In addition to positing the first hypothesis of inter-relationships between Mancallinae species, phylogenetic results support placement of Mancallinae as the sister taxon to all other Alcidae, indicating that flightlessness evolved at least twice in the alcid lineage. Convergent osteological characteristics of Mancallinae, the flightless Great Auk, and Spheniscidae are summarized, and implications of Mancallinae diversity, radiation, and extinction in the context of paleoclimatic changes are discussed.
Highlights
Alcidae Leach 1820 is a clade of pelagic wing-propelled-diving Charadriiformes Huxley 1867 including 23 extant species with an exclusively northern hemisphere distribution
Similar to the hypothesized independent evolution of flightlessness in penguins and plotopterids (Smith 2010), the placement of Mancallinae as the sister taxon to crown Alcidae suggests that flightlessness evolved independently in the Mancallinae and Pinguinus lineages, making the many osteological characteristics shared between these taxa an even more compelling example of morphological convergence
The phylogenetic position of Mancallinae as the sister taxon to all other Alcidae suggests extensive ghost lineages in Pan-Alcidae, provides further evidence that the charadriiform fossil record is quite incomplete, and demonstrates that flight was lost independently in at least two lineages of alcids
Summary
Alcidae Leach 1820 is a clade of pelagic wing-propelled-diving Charadriiformes Huxley 1867 including 23 extant species with an exclusively northern hemisphere distribution (del Hoyo et al 1996). Phylogenetic analyses of molecular data with dense taxonomic sampling for Alcidae support the monophyly of an extant alcid clade (Thomas et al 2004; Baker et al 2007; Pereira and Baker 2008). The recent morphology based analyses of Livezey and Zusi (2006, 2007) Livezey (2009, 2010) and Mayr (2011) included Alcidae as a single, taxon level terminal
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