The problem with this graph is that before 500 years ago, extinction rates are approximated from studying fossils, which is a notoriously unreliable method of measuring extinction rates. As explained in the textbookBiodiversity and Environmental Philosophy, the “benchmark for assessing the severity of...
Smith RMH, Botha-Brink J (2014) Anatomy of a mass extinction: sedimentological and tapho- nomic evidence for drought-induced die-offs at the Permo-Triassic boundary in the main Ka- roo Basin, South Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 396:99-118....