Morphometric identification of bovid metapodials to genus and implications for taxon-free habitat reconstruction

Principal Components Analysis (PCA) of measurements on twelve metacarpal and ten metatarsal dimensions indicates that metapodials differ much more in size than in shape among the twenty-three genera of extant Sub-Saharan bovids. The only conspicuous shape variation is in metapodial length, which sometimes differs significantly among genera that are similar in all other dimensions. It follows that Discriminant Analysis (DA) intended to identify metapodials to genus will depend primarily on size, and except for the occasional like-sized genera that differ in metapodial length, DA will often confuse genera of similar size. DA of the same metapodials subjected to PCA supports this prediction. PCA further shows that bovid species that favor the same habitat often differ in metapodial size, shape, or both, and species that favor different habitats often overlap substantially in their metapodial morphometrics. DA intended to assign metapodials to habitat will thus produce different results depending on the species used to characterize each habitat type and on the number of specimens by which each species is represented. Habitat reconstruction founded in DA is therefore taxon dependent rather than taxon-free, and it cannot supplant reconstruction based on taxonomic identifications below the family level.