A Molecular View of Primate Supraordinal Relationships from the Analysis of Both Nucleotide and Amino Acid Sequences

Abstract

The fossil record suggests that the orders of eutherian mammals arose in a burst of adaptive radiation at the dawn of the Cenozoic (Savage and Russell, 1983). Possibly because of the apparent bushlike pattern of this radiation, establishing the course of phylogenetic branching that led to the orders and suborders of eutherian mammals has proven difficult. Although some regard this radiation as an almost simultaneous emergence of major clades (Simpson, 1978), most feel that such phylogenies are not actually bushlike (Gingerich, 1985; Novacek, 1990), although several splitting events may be close enough in time and in character to represent a considerable challenge for molecular and morphological analyses.