Variation and taxonomy of Asiamerican eutherian mammal Paranyctoides

Abstract

A parsimony analysis of the distribution of 408 characters in 73 taxa of Cretaceous eutherians and related taxa places three species of Paranyctoides, the Asiatic P. quadrans and the North American P. sternbergi and P. maleficus, into a monophyletic taxon supported by three unambiguous synapomorphies. In this analysis P. quadrans has three autapomorphies, but in the analysis using combined terminal taxon for the entire sample of North American Paranyctoides two of these autapomorphies (development of stylar cusps C and D on upper molars) disappeared because these characters are also variably present in the North American sample. The remaining autapomorphy of P. quadrans, m3 shorter than m2, is known from a single specimen and also may be affected by individual variation. The North American sample of Paranyctoides cannot be clearly separated into distinct species on morphological or morphometric grounds and is considered as representing a single species, P. sternbergi Fox, 1979 (= P. maleficus Fox, 1984, syn. nov.). It differs from the Asiatic P. quadrans (Nesov, 1993) only in having a sharp lingual ridge on p5 and m3 longer than m2. Paranyctoides is the sister taxon to Zhelestidae; this clade is supported by four unambiguous synapomorphies.