A review of the Guadalupian (middle Permian) global tetrapod fossil record

Until recently, the Guadalupian (middle Permian) tetrapod fossil record was known almost exclusively from the Karoo Basin of South Africa and the Cis-Urals region of Russia, limiting progress towards understanding global middle Permian tetrapod biogeography. Recent work has shed light on several new or under-explored Guadalupian tetrapod-bearing basins, and we review and synthesize these findings here. We also review changes to the international and Russian Guadalupian time scales and present updated biostratigraphic correlations for all of the basins discussed. In general, there are few tetrapod genera or species shared between mid-Permian basins, a pattern starkly different from the generic cosmopolitanism seen during Lopingian (late Permian) times. The Paraná Basin of Brazil has produced a unique fauna that combines typical South African and Russian clades, suggesting a pathway for faunal interchange between the northern and southern portions of Pangea. The Dashankou fauna of China yields basal therapsids that suggest a northern Pangean origin for this clade. The Sundyr Assemblage of Russia preserves a latest Guadalupian fauna that seems to illustrate patterns of faunal turnover across the Guadalupian-Lopingian boundary. Continued field work in the lesser-known mid-Permian strata will facilitate testing hypotheses about the transition between early and middle Permian faunas, the end-Guadalupian extinction event, Pangean tetrapod biogeography, and the origins of widespread late Permian clades.