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The higher-level systematics of the mammalian infraclass Eutheria is investigated with protein sequences of seven polypeptide types combined in an extended tandem alignment. Evolutionary trees constructed from the sequence data by the maximum-parsimony algorithm depict five major lineages of living eutherian orders which are treated as superorders in a phylogenetic classification. Glires (orders Lagomorpha, Primates, and Rodentia) and Therictoidea (Carnivora, Chiroptera, Insectivora, Pholidota, and Scandentia) constitute extant sister groups which are allied to the superorders Ungulata (Artiodactyla, Cetacea, and Perissodactyla), Paenungulata (Hyracoidea, Proboscidea, Sirenia, and Tubulidentata), and Edentata in that order. As sequence data for extant mammalian taxa continue to accumulate, we anticipate that many remaining questions about eutherian phylogeny will be resolved.
Miyamoto et al. (Sun,) studied this question.