Relationships of lungfishes

Problems surrounding the relationships of lungfishes are intricately connected with the search for the origin of tetrapods. Early in the history of lungfish research, the emphasis was on attempts to determine whether lungfishes were more closely related to fishes or to tetrapods. Later there was a shift towards a search for particular ancestors and ancestral groups, an approach that not only introduced problems relative to the concept of ancestry but also stultified attempts to classify the sarcopterygians. Cladistic analysis, on the other hand, has placed the inquiry into lungfish relationships on a surer footing, in which alternative theories are more open to criticism. It is concluded that, among Recent taxa, lungfishes and tetrapods are sistergroups, with coelacanths as the plesiomorphic sister-group to that combined group. Rhipidistians are a paraphyletic group distributed amongst the Recent taxa.