Phyllocarida and the origin of the Malacostraca

Tentative homologies with Decapoda are proposed for grooves on the carapace of Echinocaris and Montecaris. Together with F.R. Schram's hoploid trend, reinforced by the discovery of a raptorial limb in Sairocaris, this may strengthen a phyllocarid origin for Eumalacostraca. Both these trends, however, may be parallelisms, and phylogenetic analysis is required. Pleopods are here proved to have been present in additional Archaeostraca, which improves their ancestral condition. E. Dahl's view of the phyllocarids as an evolutionary dead end is falsified from fossils, and the phyllocarids are supported as a stem group of the Malacostraca.