Integrated analysis of fossils and molecular divergence time estimates a latest Jurassic origin of angiosperms.

Molecular timescales are based on the calibration of molecular evolution to geological time using fossil constraints, but conventional calibration strategies use limited and often subjectively interpreted fossil data. Here we used the Bayesian Brownian Bridge model to derive data-driven calibration densities on the basis of extensive fossil occurrence data. This approach integrates the uncertainty on extant and historical diversity to estimate clade age. We transformed the estimated ages based on >25,000 fossil occurrences into calibration densities, which we used to constrain 110 node ages in a 644-species angiosperm phylogenetic tree inferred from a molecular alignment of 83 genes. The results are incompatible with a post-Jurassic origin of angiosperms, instead inferring a short, Late Jurassic history. Our study demonstrates the utility of a mechanistic approach to establish node-age constraints in molecular-clock-dating analyses, resulting in a more objective method to integrate molecular and palaeontological data when inferring evolutionary timescales.