Cladistic analysis of the total ontogenetic pattern of the fetal membranes and placenta in all extant primate superfamilies provides clear evidence of a strepsirhine-haplorhine dichotomy in the order Primates. The suborder Prosimii appears to be a paraphyletic taxon, based on the retention of numerous primitive character states in tarsiers and strepsirhines. Fetal membrane evidence supports the sister group relationship of Tarsiiformes and Anthropoidea in the suborder Haplorhini, based on their possession of shared derived characters. Morphogenetic patterns of the fetal membranes and placenta in haplorhines are consistent with the concept of a monophyletic origin of Anthropoidea from an ancestral tarsilform stock.