O'Leary, M. A. Geisler, J. H. 1999 The position of Cetacea within Mammalia: phylogenetic analysis of morphological data from extinct and extant taxa Systematic Biology 48 455-490 Didelphis Asioryctes Leptictis Arctocyon Hyopsodus Phenacodus Meniscotherium Heptodon Hyracotherium Equus Diacodexis Archaeotherium Elomeryx Hippopotamus Hexaprotodon Sus Agriochoerus Poebrotherium Camelus Ovis Tragulus Andrewsarchus Eoconodon Hapalodectes Dissacus Ankalagon Sinonyx Pachyaena Mesonyx Synoplotherium Harpagolestes Pakicetus Ambulocetus Remingtonocetus Cross_Whale Protocetus Basilosaurus Dorudon Balaenopterua Turslops Osteology Maximum Parsimony Based on reanalysis of the original matrix. OLeary_et_Geisler_1999a