stratigraphy of the United Kingdom (and Western Europe as a whole), the Serpukhovian corresponds to the lower half of the Namurian regional stage. This portion of the Namurian includes three substages, from oldest to youngest: the Pendleian, Arnsbergian and Chokierian. Only the lowermost Chokierian falls in the Serpukhovian, the upper part of the substage corresponds to the earliest Bashkirian. In North America, the Serpukhovian corresponds to the upper part of the Chesterian regional stage, while in China the Serpukhovian is roughly equivalent to the Dewuan regional stage. Serpukhovian extinction The largest extinction event of the Carboniferous Period occurred in the early Serpukhovian. This extinction came in the form of ecological turnovers, with the demise of diverse Mississippian assemblages of crinoids and rugose corals. After the extinction, they were replaced by species-poor cosmopolitan ecosystems. The extinction selectively targeted species with a narrow range of temperature preferences, as cooling seawater led to habitat loss for tropical specialists. In the following Late Paleozoic ice age of the Late Carboniferous and Early Permian, both speciation and extinction rates were low. This may have been driven by a reduction of carbonate platforms, which otherwise would have helped to maintain high biodiversity. The long-term ecological impact of the Serpukhovian extinction may have exceeded that of the Ordovician-Silurian extinction, where taxonomic diversity was abruptly devastated but quickly recovered to pre-extinction levels. Sepkoski (1996) plotted an extinction rate of around 23-24% for the Serpukhovian as a whole, based on marine genera which persist through multiple stages. Bambach (2006) found an early Serpukhovian extinction rate of 31% among all marine genera. Using an extinction probability procedure generated from the Paleobiology Database, McGhee et al. (2013) estimated an extinction rate as high as 39% for marine genera. On the other hand, Stanley (2016) estimated that the extinction was much smaller, at a loss of only 13-14 % of marine genera. Relative to other biological crises, the Serpukhovian extinction was much more selective in its effects on different evolutionary faunas. Stanley (2007) estimated that the early Serpukhovian saw the loss of 37.5% of marine genera in the Paleozoic evolutionary fauna. Only 15.4% of marine genera in the modern evolutionary fauna would have been lost along the same time interval. This disconnect, and the severity of the extinction as a whole, is reminiscent of the Late Devonian extinction events. Another similarity is how the Serpukhovian extinction was seemingly driven by low rates