Monocot fossils suitable for molecular dating analyses

Abstract

Recent re-examinations and new fossil findings have added significantly to the data available for evaluating the evolutionary history of the monocotyledons. Integrating data from the monocot fossil record with molecular dating techniques has the potential to help us to understand better the timing of important evolutionary events and patterns of diversification and extinction in this major and ancient clade of flowering plants. In general, the oldest well-placed fossils are used to constrain the age of nodes in molecular dating analyses. However, substantial error can be introduced if calibration fossils are not carefully evaluated and selected. Here we propose a set of 34 fossils representing 19 families and eight orders for calibrating the ages of major monocot clades. We selected these fossils because they can be placed in particular clades with confidence and they come from well-dated stratigraphic sequences. As more fossils are discovered or re-examined, these criteria can also be applied to expand the list of the fossils that are most suitable for dating the early branches of monocot phylogeny.