AN EXAMINATION OF THE PHYLOGENETIC POSITION OF THE EMBOLOMERI

Recent phylogenetic studies of early tetrapods have produced phylogenies that contradict the traditional belief that anthracosaurs are the sister group to amniotes while temnospondyls are the sister group to the lissamphibia. In order to test the monophyly of the Embolomeri, a group of Carboniferous and Permian anthracosaurs, additional embolomeres were added to the data matrix of Laurin (1998) and coded based upon published descriptions. Added to the database were the following embolomere taxa: Anthracosaurus, Carbonerpeton, Calligenethlon, Eoherpeton, Palaeogyrinus, Pholiderpeton, and Pteroplax. The resulting data set contained 52 taxa and 155 characters, thirteen of which are anthracosaurs under the traditional definition. The heuristic algorithm of PAUP* (Swofford, 1999) produced 6 most parsimonious trees from this dataset. The Adams consensus tree produced from the most parsimonious trees contains a monophyletic clade containing both the Embolomeri and the Gephyrostegidae. Excluded from this clade are the seymouriamorphs, the third group traditionally included within the Anthracosauria. Instead the seymouriamorphs are included within a larger clade that includes both amniotes and extant amphibians. The combined Emobolmeri and Gephyrostegidae is a sister group to this larger amniote, amphibian, and seymouriamorph clade. This relationship is not robustly supported, one thousand bootstrap replicates produced confidence values below 50 percent for the embolomere + gephyrostegid clade. Removal of embolomere taxa with significant percentages of missing data did not increase support in a second bootstrap.