Morphology's role in phylogeny reconstruction: perspectives from paleontology.

A recent article by Scotland et al. (2003; hereafter referred to as SEA) purporting to examine the value of morphological data in phylogeny reconstruction has been received critically by several systematists (Jenner, 2004; Wiens, 2004). As paleontologists—and in an area of systematics restricted solely to morphological data—we take exception to many of the arguments put forward by SEA and feel we may provide a unique perspective in the debate. In their paper, SEA argued for a redefined role for morphology in phylogeny reconstruction, one in which “rigorous and critical anatomical studies of fewer morphological characters, in the context of molecular phylogenies, is a more fruitful approach to integrating the strengths of morphological data with those of sequence data” (p. 539). Such a statement is bold and therefore warrants a critical analysis, as it would effectively neuter the ability of morphological data to generate novel phylogenies. Though issues such as accuracy, support, character coding, and character conceptualization were discussed by SEA, in all cases these discussions resorted to a “too few characters” argument. As the authors characterized it, the “main constraint of morphology-based phylogenetic inference concerns the limited number of unambiguous characters available for analysis in a transformational framework” (p. 539). Additionally, the merits of increased taxon sampling in the context of morphological data were discussed by SEA, and found to be lacking. Though several of the views presented by SEA are not novel (see Hedges and Sibley, 1994, and Hedges and Maxson, 1996), they provide the most detailed recent discussion of this position. We agree with many of the points made by SEA, especially the call for more critical and rigorous analysis of morphology; however, we draw different conclusions from the data. It is our goal to reexamine some of the arguments put forward by SEA, in order to illustrate that a much more optimistic conclusion exists regarding the current and future role of morphology in phylogeny reconstruction.