1. Departments of Biological Sciences, Mathematics, and Preventive Medicine, University of Southern California, Los Angeles, California 90089-1340, USA
2. Departments of Organismic and Evolutionary Biology, and Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA
3. Department of Statistics, University of Washington, Seattle, Washington 98195, USA
4. Anthropologisches Institut & Museum, Universität Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
5. Human Origins Group, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
6. Academic Affairs, Field Museum, Chicago, Illinois 60605-2496, USA

Correspondence to: Simon Tavaré¹ Correspondence and requests for materials should be addressed to S.T. (e-mail: Email: stavare@usc.edu).

Divergence times estimated from molecular data often considerably predate the earliest known fossil representatives of the groups studied. For the order Primates, molecular data calibrated with various external fossil dates uniformly suggest a mid-Cretaceous divergence from other placental mammals, some 90 million years (Myr) ago^{1, 2, 3, 4, 5, 6, 7, 8, 9}, whereas the oldest known fossil primates are from the basal Eocene epoch (54–55 Myr ago). The common ancestor of primates should be earlier than the oldest known fossils^{10, 11}, but adequate quantification is needed to interpret possible discrepancies between molecular and palaeontological estimates. Here we present a new statistical method, based on an estimate of species preservation derived from a model of the diversification pattern, that suggests a Cretaceous last common ancestor of primates, approximately 81.5 Myr ago, close to the initial divergence time inferred from molecular data. It also suggests that no more than 7% of all primate species that have ever existed are known from fossils. The approach unites all the available palaeontological methods of timing evolutionary events: the fossil record, extant species and clade diversification models.