Phylogenetic Utility of Mammalian Postcranial Characters

Abstract

In phylogenetic studies of extinct species, researchers often exclude postcranial data because postcranial elements are missing, underrepresented, or difficult to assign to particular species. However, in some cases these decisions revolve around the idea that postcranial data are inappropriate for phylogenetic analyses because they are functionally or developmentally integrated or otherwise “prone to homoplasy.” In this study, we used a character congruence approach to test the hypothesis that postcranial data cannot be used to reconstruct phylogenies instead of the taxonomic congruence approaches most often employed in paleoanthropological studies. We identified 98 published mammalian phylogenetic datasets that included sufficient numbers of characters from the skull, dentition, and postcranium to be included in the analysis. We calculated partitioned Bremer support (PBS) values for each data partition on each strict consensus cladogram using the programs Phylogenetic Analysis Using Parsimony (PAUP) v. 4.0b10 and TreeRot.v3, calculated partition congruence indices (PCI), and assessed significant differences between data partitions using Fischer's least significant difference test. Averaged across each cladogram, postcranial PBS values are greater than, or not significantly different from, 69.4% of skull PBS values (68 studies) and 64.3% of dental PBS values (63 studies). Postcranial data provided primary support (“winning sites”) at 301/1448 nodes (20.8%), exhibited positive values at 710/1483 nodes (47.9%), and “do no harm” at 1196/1483 nodes (80.6%). There is no correlation between PBS values and data partition size as long as there are at least ten characters in each data partition. These results highlight the potential for using postcranial data to construct hominin phylogenies and argue against their exclusion from phylogenetic analyses for a priori reasons.Support or Funding InformationUndergraduate student research in this study was supported by the Benedictine University Natural Science Summer Research Program.