An Alphataxonomic Revision of Extinct and Extant Razorbills (Aves, Alcidae): A Combined Morphometric and Phylogenetic Approach

Abstract

Abstract.— Alca (Aves, Alcidae) has a comparatively rich fossil record with respect to other Charadriiformes, consisting of thousands of specimens. Despite the abundance of fossil material, species richness in this clade has remained poorly understood, primarily because of the paucity of associated specimens. To address this issue, a combined morphometric and apomorphy-based method was developed that would allow referral of fragmentary and isolated specimens, which constitute ~97% of the Alca fossil record. Measurements of multiple variables from >2,000 Alca fossils were categorized by hierarchical cluster analysis and resulted in the recognition of "species clusters." Discriminant function analysis was used to assess statistical support for these clusters and to identify the most informative measurements with respect to discriminating between species on the basis of size. The reliability of this method was tested using the same measurements taken from 13 extant alcid species and was found to be robust wi...