Data from: Geomolecular dating and the origin of placental mammals

Molecular dating has been transformed by relaxed clock methods that allow the rate of molecular evolution to vary across the phylogeny (Sanderson 1997; Thorne and Kishino 2002; and see Welch and Bromham 2005). Single point calibrations have in turn been superseded by multiple sets of calibration bounds or priors. As a result, geological information, which formerly only gave a temporal scale to molecular branch lengths now also substantially informs how rates of molecular evolution vary across the tree (see Ho and Phillips 2009; Magallón et al. 2013). I refer to this modern conception of relaxed clocks and multiple calibrations as geomolecular dating. Despite recent progress in modelling molecular sequence evolution, large apparent conflicts with far younger fossil records remain across the tree of life, such as for the diversification of metazoans (Aris-Brosou and Yang 2002), and the origins of flowering plants (Bell et al. 2010) and birds (Brown et al. 2008). The timing of placental mammal diversification remains especially contentious, with major recent studies reinforcing divisions between older, molecular-based estimates (Meredith et al. 2011; Bininda-Emonds et al. 2012) and younger fossil-based estimates (Wible et al. 2007; O’Leary et al. 2013).