The well-accepted Euarchonta grandorder is a pruned version of Archonta nested within the Euarchontoglires(or Supraprimates)clade.At present,it includes tree shrews(Scandentia),flying lemurs(Dermoptera)and primates(Primates).Here,a phylogenomic dataset containing 1912 exons from 22 representative mammals was compiled to investigate the phylogenetic relationships within this group.Phylogenetic analyses and hypothesis testing suggested that tree shrews can be classified as a sister group to Primates or to Glires or even as a basal clade within Euarchontoglires.Further analyses of both modified and original previously published datasets found that the phylogenetic position of tree shrews is unstable.We also found that two of three exonic indels reported as synapomorphies of Euarchonta in a previous study do not unambiguously support the monophyly of such a clade.Therefore,the monophyly of both Euarchonta and Sundatheria(Dermoptera+Scandentia)are suspect.Molecular dating and divergence rate analyses suggested that the ancestor of Euarchontoglires experienced a rapid divergence,which may cause the unresolved position of tree shrews even using the whole genomic data.
