Hexapod origins: Monophyletic or paraphyletic?

Recent morphological and molecular evidence has changed interpretations of ar- thropod phylogeny and evolution. Here we compare complete mitochondrial ge- nomes to show that Collembola, a wingless group traditionally considered as basal to all insects, appears instead to constitute a separate evolutionary lineage that branched much earlier than the separation of many crustaceans and insects and independently adapted to life on land. Therefore, the taxon Hexapoda, as com- monly defined to include all six-legged arthropods, is not monophyletic.