Did the end-Cretaceous mass extinction event, by eliminating non-avian dinosaurs and most of the existing fauna, trigger the evolutionary radiation of present-day mammals? Here we construct, date and analyse a species-level phylogeny of nearly all extant Mammalia to bring a new perspective to this question. Our analyses of how extant lineages accumulated through time show that net per-lineage diversification rates barely changed across the Cretaceous/Tertiary boundary. Instead, these rates spiked significantly with the origins of the currently recognized placental superorders and orders approximately 93 million years ago, before falling and remaining low until accelerating again throughout the Eocene and Oligocene epochs. Our results show that the phylogenetic ‘fuses’ leading to the explosion of extant placental orders are not only very much longer than suspected previously, but also challenge the hypothesis that the end-Cretaceous mass extinction event had a major, direct influence on the diversification of today’s mammals.
D. Wong and A. Mooers provided their unpublished supertree of Geomyoidea. T. Barraclough, J. Bielby, N. Cooper, T. Coulson, M. Crawley, J. Davies, S. Fritz, N. Isaac, A. Lister, K. Lyons, G. Mace, S. Meiri, D. Orme, G. Thomas and N. Toomey all provided support and/or suggestions to improve the manuscript. Funding came from the NCEAS Phylogeny and Conservation Working Group; the BMBF; a DFG Heisenberg Scholarship; NERC studentships and grants; the Leverhulme Trust; the NSF; an Earth Institute Fellowship; and a CIPRES postdoctoral fellowship.
Author Contributions O.R.P.B.-E. developed data and computer protocols underlying the supertree and dating analyses, contributed to or performed many of the supertree analyses, generated the molecular data set and dated the supertree, and wrote major portions of the manuscript; M.C. helped develop data protocols, contributed source trees and performed many of the intraordinal supertree analyses, and helped write parts of the manuscript; K.E.J. contributed source trees, developed data protocols, collected the fossil database and performed associated analysis; R.D.E.M. provided relevant palaeontological information and first appearance dates of major clades, and collected the fossil database and performed associated analysis; R.M.D.B. contributed to and performed selected supertree analyses, and provided relevant palaeontological information; R.G. developed protocols for and performed supertree construction and macroevolutionary analyses, and contributed to the writing of the manuscript; S.A.P. developed data protocols, collected source trees for and built the cetartiodactyl and perissodactyl portions of the supertree; R.A.V. provided source trees for Primates; J.L.G. provided source trees and ideas for comparative tests; and A.P. developed, conceived and performed the macroevolutionary analyses, wrote the corresponding sections of the manuscript and developed data protocols. All authors provided comments on the manuscript.
This file represents Supplementary Table 2 and presents a summary of the taxonomic identity and divergence time estimates for each node on the supertree.
This file was amended on 13 November 2008 because the authors discovered a bug in the Perl script relDate v.2.2 that was used in part to date the nodes in the species-level mammalian supertree presented and analysed in their Article and original Supplementary Information; see the related Corrigendum (nature07347).
This file represents Supplementary Table 5 and summarizes the occurrence of mammalian genera in 11subepochs from the Late Triassic until Late Eocene using data from the Unitaxon database.