Stability of phylogenetic results to the exclusion of particular taxa from the total combined data matrix.

Taxa deleted in each parsimony search are indicated above the phylogenetic result for each reanalysis. For simplicity, only the placements of major extant lineages and three critical fossil groups (†Mesonychia, †Creodonta, and †Raoellidae) are shown in the figure. Successive deletion of particular taxa from analysis results in contradictory interpretations of phylogenetic relationships. With the removal of Lipotyphla + †Creodonta, note that two equally parsimonious “islands” of trees are supported (†Mesonychia deep within Artiodactyla or completely outside the clade). †Creodonta is excluded from Artiodactyla in most reanalyses, but with the removal of Lipotyphla and Carnivora, †Creodonta clusters with †Mesonychia in a clade that is the sister group to Cetacea. Illustrations are by C. Buell and L. Betti-Nash.