Ancestor Of All Primates.

A new comprehensive genetic analysis shows that flying lemurs known as colugos is our closest nonprimate cousin. This is the result of a two-pronged molecular study by Jan Janecka, a postdoctoral fellow working with evolutionary genomicist William Murphy at Texas A&M University. Both analyses brought flying lemurs closer to primates than they had ever been before. The new study shows that the ancestors of tree shrews split off first, and then the primate and colugo lineages diverged. The new evolutionary study also shows that the pentail tree shrew is the sole survivor of an ancient lineage long separated from other tree shrew species.
For more details refer to
Molecular and Genomic Data Identify the Closest Living Relative of Primates
Jan E. Janecka,Webb Miller,Thomas H. Pringle,Frank Wiens, Annette Zitzmann, Kristofer M. Helgen,Mark S. Springer,William J. Murphy

Science 2 November 2007:
Vol. 318. no. 5851, pp. 792 - 794
DOI: 10.1126/science.1147555