PHYLOGENETIC ANALYSIS AND ORDINAL CLASSIFICATION OF THE BRACHIOPODA

The long-standing division of the lophophorate Phylum Brachiopoda into two units of Class rank, the Articulata and Inarticulata, is not supp orted by phylogenetic (cladistic) analysis. Using the PAUP program, tw o separate analyses, for seven extant brachiopod orders/suborders and for the combined extant and extinct groups, respectively, are consiste nt in identifying all chitinophosphatic-shelled stocks as a sister gro up to the carbonatic-shelled brachiopods, which include both 'inarticu lates' and 'articulates' of previous schemes. The chitinophosphatic-sh elled stocks are united in the Class Lingulata, but within the Brachio poda, contrary to the proposals of Gorjansky and Popov (1985). The car bonatic-shelled brachiopods form the Class Calciata, embracing the Sub class Craniformea (including Craniida, Craniopsida, and Trimerellida), and a yet un-named Subclass that includes the Obolellida, Kutorginida , and the 'articulates'. The precise affinities of the kutorginides re main enigmatic, although they are clearly calciate. The proposed relat ionships suggest that brachiopods are monophyletic and had consistentl y separate shell chemistries from early in their phylogeny, removing t he need for the repeated transformations in biomineralization inherent in previous evolutionary models.