Bulletin of the Mizunami Fossil Museum, no. 31 (2004), p. 1-19, 7 figs., 1 table. c 2004, Mizunami Fossil Museum Decapod phylogeny: addition of fossil evidence to a robust morphological cladistic data set Frederick R. Schram 1 and Christopher J. Dixon 2 1 Zoological Museum, University of Amsterdam, Mauritskade 57, NL-1092 AD Amsterdam, The Netherlands <
[email protected]> 2 Institut für Botanik, University of Vienna, Rennweg 14, A-1030 Vienna, Austria 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. Key words: Decapoda, phylogeny, cladistics clades, viz., groups they termed Fractosternalia [Astacida Introduction + Thalassinida + Anomala + Brachyura], and Meiura [Anomala + Brachyura]. Schram (2001) later computerized Taxonomies of Decapoda have typically been constructed their analysis, allowing a more objective view of similar either with almost no regard to the fossil record, or, in a data.