Agradecimentos: This is contribution 366 of the Evolution of Terrestrial Ecosystems consortium at the National Museum of Natural History, in Washington, DC. N.W. acknowledges funding from the Swedish Research Council [2015-04441.] and from the Department of Biology, Lund University. A.V.L.F. thanks the CNPq [303834/2015-3], the National Science Foundation [DEB-1256742], and FAPESP [2011/50225-3]. This publication is part of the RedeLep (Rede Nacional de Pesquisa e Conservação de Lepidópteros) SISBIOTABrasil/CNPq [563332/2010-7]. M.H. gratefully acknowledges funding from a Peter Buck Postdoctoral Stipend, Smithsonian Institution National Museum of Natural History. J.C.S. is receiving supports from the Research Under Protection program [NRF 2017R1D1A2B05028793], funded by the National Research Foundation of Korea Ver menos

Abstract: The need for robust estimates of times of divergence is essential for downstream analyses, yet assessing this robustness is still rare. We generated a time-calibrated genus-level phylogeny of butterflies (Papilionoidea), including 994 taxa, up to 10 gene fragments and an unprecedented set of 12 fossils and 10 host-plant node calibration points. We compared marginal priors and posterior distributions to assess the relative importance of the former on the latter. This approach revealed a strong influence of the set of priors on the root age but for most calibrated nodes posterior distributions shifted from the marginal prior, indicating significant information in the molecular data set. Using a very conservative approach we estimated an origin of butterflies at 107.6 Ma, approximately equivalent to the latest Early Cretaceous, with a credibility interval ranging from 89.5 Ma (mid Late Cretaceous) to 129.5 Ma (mid Early Cretaceous). In addition, we tested the effects of changing fossil calibration priors, tree prior, different sets of calibrations and different sampling fractions but our estimate remained robust to these alternative assumptions. With 994 genera, this tree provides a comprehensive source of secondary calibrations for studies on butterflies Ver menos