Note: This is the latest version of the Permian timescale which SPS recommends (Shen et al., 2013, pdf). We welcome any comments to improve it. All the information will be updated from time to time here. Geochronologic ages are combined from Burgess et al. (2014, PNAS); Shen et al. (2011, Science) for the Lopingian; Zhong et al. (Lithos, 2014) for the Guadalupian-Lopingian boundary; Schmitz and Davydov, 2012 (GSA Bulletin) for the Cisuralian, Henderson et al. (2012, GST) for the base of Kungurian and the Guadalupian. Tetrapod biochronology is after Lucas (2006, Geological Society, London, Special Publications, Vol. 265, p. 65-93).