HIGHER TAXONOMIC RELATIONSHIPS AMONG EXTANT MAMMALS BASED ON MORPHOLOGY, WITH SELECTED COMPARISONS OF RESULTS FROM MOLECULAR-DATA

Until a few decades ago, phylogenetic relationships among placental or ders were ambiguous and usually depicted to radiate as an unresolved ' 'bush.'' Resolution of this bush by various workers has been progressi ng slowly, but with promising results corroborated by nondental, denta l, and molecular characters. In this study we continue to seek resolut ion. A total of 258 nondental and 2 dental characters was analyzed by PAUP and MacClade on 39 vertebrate taxa (3 reptiles, 1 nonmammalian th erapsid, and 35 mammals; 20 of the mammals are extant and 15 are extin ct) to study higher taxonomic relationships with emphasis on Placental ia (Eutheria). About two-thirds of the characters are osteological, th e rest concern soft tissues, including myological but excluding molecu lar characters (most are our data, the rest are from the literature). Cladistic analysis included all 39 taxa (fossil taxa help to evaluate polarities of characters) and all characters were given equal weight. Extant Mammalia are divided into Prototheria and Theria, the latter in to Marsupialia and Placentalia. Placentalia comprises Xenarthra and Ep itheria. Within Epitheria, Lipotyphla and Preptotheria (emended) are s ister-taxa. Preptotherian taxa group into: ungulate-related taxa and v arious nonungulates. The former include Carnivora, Pholidota, Tubulide ntata, Artiodactyla, Cetacea, Perissodactyla, Hyracoidea, Proboscidea, and Sirenia. A possible association to embrace Lagomorpha, Rodentia, Macroscelidea, Scandentia, Primates, Chiroptera, and Dermoptera is sug gested. Significant differences between our findings and those of rece nt investigators include the dissociation of Pholidota from Xenarthra and the plesiomorphous position of Lipotyphla within Epitheria. Congru ence between morphological and molecular results is closer than previo usly reported. (C) 1998 Academic Press.