Decapod phylogeny: addition of fossil evidence to a robust morphological cladistic analysis

Abstract

Incorporating fossils into schemes for the phylogenetic relationships of decapod crustaceans has been difficult because of the generally incomplete nature of the fossil record. Now a fairly robust data matrix of characters and taxa relevant to the phylogeny of decapods has been derived from consideration of living forms. We chose several taxa from the fossil record to test whether the robustness of the matrix can withstand insertion of fossils with various degrees of incomplete information. The essential structure of the original tree survives, and reasonable hypotheses about the affinities of selected fossils emerge. Sometimes we detected singular positions on our trees that indicate a high certainty about where certain taxa fit, while under other conditions there are alternative positions to choose from. Definitive answers are not to be expected. Rather, what is important is the demonstration of the usefulness of a method that can entertain and specifically document multiple alternative hypotheses.