central Africa. The Late Famennian glacial phase, along with other short glacial phases in the Tournaisian and Visean, acted as a prelude to the far larger and more prolonged Late Paleozoic Ice Age which stretched across much of the Late Carboniferous and Early Permian. Aftershocks - the upper crisis interval The upper crisis interval begins with the return of prominent carbonate rocks: a marly unit, the Stockum Limestone, spans the Devonian-Carboniferous (D-C) boundary. Foraminifera reappear in the fossil record within the Stockum Limestone, forming the DFZ8 zone characterized by Tournayellina pseudobeata. The base of the Stockum Limestone also sees the beginning of the Protognathodus kockeli conodont zone and further ammonoid diversification within the upper Acutimitoceras (Stockumites) genozone (LC I-A1). A major extinction among land plants and palynomorphs indicates the beginning of the VI spore zone shortly before the D-C boundary. ‘Survivor’ faunas of marine invertebrates, such as the last cymaclymeniid ammonoids and phacopid trilobites, also die out at this time, making it the second largest extinction pulse of the Hangenberg Crisis. Conodont zones (usually characterized by Protognathodus kuehni or Siphonodella/Eosiphonodella sulcata) define the D-C boundary, but difficulty in finding reliable and universal index taxa has complicated study of the boundary in many areas. The sea level fluctuated during the upper crisis interval, as several minor regressions and transgressions continued to occur around the D-C boundary. Nevertheless, the general trend was sea level rise, with the melting of the glaciers which formed in the middle crisis interval. In the early Tournaisian, the crisis finally ends at the base of the Hangenberg Limestone, a fossiliferous limestone superficially similar to the pre-crisis Wocklum Limestone. The base of the Hangenberg Limestone is characterized by the first occurrence of gattendorfiine ammonoids (making up the Gattendorfia genozone, LC I-A2) and the MFZ1 foraminifera zone. Extinction severity Along with the other two stages in the Late Devonian, the Famennian was qualitatively acknowledged as having elevated extinction rates as early as Raup and Sepkoski's 1982 landmark paper on mass extinctions. However, late Famennian extinction rates were typically considered to be of lesser taxonomic severity than those in the Kellwasser Event, one of the “big five” mass extinctions. Depending on the method used, the Hangenberg Event typically falls between the fifth and tenth deadliest post-Cambrian mass extinctions, in terms of marine genera lost. Most estimates of proportional extinction have low resolution, only as fine as the stages in which