The relationships within the superorder Archonta, which contains the orders Dermoptera (flying lemurs), Scandentia (tree shrews), Chiroptera (bats), and Primates, were examined through the analysis of five newly derived and complete mitochondrial 12S rRNA sequences. The new data is combined with 83 additional known mammalian sequences to provide a full phylogenetic sampling. Phylogenetic hypotheses are generated using PAUP 3.1.1 (Swofford [1993] Illinois Natural History Survey, Champaign, IL) through analyses of all characters equally weighted, transversions only, and the effect of alignment gaps on phylogeny. The Parsimony Jackknifer (Farris et al. [1996] Cladistics 12:99-124) was used to assess the level of ambiguity present in the sequence data, and therefore the strength of the tree topologies. The conclusions of Springer and Douzery (1996, J. Mol. Evol. 43:357-373) which states that 12S rRNA is reliable to a time depth of 100 mya is unsupported by these analyses. The usefulness of 12S rRNA to aid in solving Archonta relationships and others of similar time depth is found to be suspect.