Royal Society Publishing

Is there any Consensus on Basal Archosaur Phylogeny?

David J. Gower, Mark Wilkinson


Studies of basal archosaur phylogeny since 1975 were reviewed to assess directly opposing views on the (dis)agreement reached as a result of adopting cladistic methodology. The transition to modern numerical cladistic analyses has been long, including two principal stages: with listing of derived characters as node support eventually replaced by explicit data and methodology presentation. All four existing explicit numerical studies are reanalysed, and a semi-strict reduced cladistic consensus is constructed for them and compared with earlier `cladistic' studies where data was not presented. The two principal steps to modern numerical analyses have been accompanied by an increase in the agreement between separate hypotheses, and there exists substantial current consensus on the resolution of many pre-cladistically vague relationships. However, Bremer support values calculated for the four numerical studies indicate that the strength of hypothesised clades is generally low to minimal. Because a previous review (Charig 1993) included many non-cladistic studies, using its failure to find consensus as a basis for broader criticisms of cladistic methods is considered unjustified. However, some of Charig's (1993) criticisms of current practises are endorsed. Reproducibility of results, greater methodological awareness, and more rigorous assessment of hypothesis robustness are identified as additional issues requiring consideration in future studies.