Fossil Specimens, Data Integration, and Phylogeny Reconstruction of Long-Lived, Modern Clades

Extinct taxa (represented by fossil specimens) provide unique repositories of morphological data that, when phylogenetically analyzed simultaneously with extant terminal taxa, can contribute important grouping structure, as well as information about the sequence and timing of evolutionary changes. While most phylogenetic hypotheses of extant taxa are constructed using exclusively molecular sequence data, a growing number of cladistic studies have combined molecular and morphological data partitions into single “total evidence” matrices and some have added extinct terminal taxa—typically not coded for any of the numerous molecular sequence characters—to these data sets. Some of these studies have found that the phylogenetic positions of extinct taxa in such simultaneous analyses can be successfully located in consensus tree topologies. Thus, the “missing data problem” has probably been overstated and, at least in some cases, may not be the perceived obstacle it was once considered. This avenue of research is inherently cross-disciplinary and has great potential for testing macroevolutionary hypotheses. This is especially the case for clades with great diversity today, but which also have numerous extinct species. An example of such a clade is the hyperdiverse marine snail genus Conus, which has a rich Eocene-Recent evolutionary history. Here we present preliminary results of a phylogenetic analysis of Conus taxa undertaken to explore the effects of combining molecular sequence data, discrete and continuous morphological data, and both actual and simulated (“pseudofossils”) extinct terminal taxa in the same matrix. The goal of this research is to explore the most effective way(s) to incorporate fossil taxa—often times represented by limited character data—into the phylogenetic context of their extant relatives, thereby providing a more complete view of the evolutionary histories of modern, but long-lived clades.