FIGURE 1. A simplified primate evolutionary tree.

The two main groups of living primates, the strepsirrhines and haplorhines, are shown, and the new fossil forms (Saharagalago and Karanisia) described by Seiffert and colleagues¹ are included. These specimens double the known age of the lineages leading to bushbabies and lorises (together, the lorisiforms), and increase the number of known lorisiform genera by half. The previously known genera are Komba, Progalago and Mioeuoticus from the early Miocene of East Africa, and Nycticeboides from the late Miocene of Pakistan. The only known fossil form potentially related to the other strepsirrhine group, the lemurs, is Bugtilemur from the early Oligocene of Pakistan. A direct reading of the fossil record indicates that primates began to diversify just after the Cretaceous/Tertiary (K/T) boundary. But, given the incompleteness of the fossil record, diversification may have occurred at least 20 million years before the K/T boundary, as indicated by the shadow tree. (Primate icons drawn by Lucrezia Beerli-Bieler.)