 Cohen and Weydman's analysis (2005) concludes that phoronids are a sub-group of inarticulate brachiopods (those in which the hinge between the two valves have no teeth and sockets) and sister-group of the other inarticulate sub-groups.The authors also suggest that the ancestors of molluscs and the brachiopod+phoronid clade diverged between 900 Ma and 560 Ma, most probably about 685 Ma.The phylum has two genera, with no class or order names.