have been found in the southern and central United States (Texas, Oklahoma, Kansas), France, Germany, Poland, Sardinia, and European Russia. This geographical distribution corresponds to the paleoequatorial belt of Pangaea during the Carboniferous and the Permian, with the exception of the Russian localities which were located at the level of the 30th parallel north where a more temperate climate prevailed. The absence in Russia of terrestrial vertebrate localities prior to the Kungurian does not allow us to know the precise moment of the arrival of caseids in this region of the world. According to Werneburg and colleagues, the presence of caseids at this paleolatitude suggests their possible existence in the temperate regions of Gondwana. A possible Gondwanan occurrence was proposed as early as the 1990s by Michael S.Y. Lee and in 2021 by Asher J. Lichtig and Spencer G. Lucas, who reinterpreted the middle Permian taxon Eunotosaurus from South Africa as a small burrowing caseid. Between these two dates, other researchers classified Eunotosaurus as a parareptile or a pantestudines. If the first three authors are correct, Eunotosaurus would be the first caseid found in the Southern Hemisphere and the last known representative of the family with a latest Capitanian age for the most recent specimens. Elsewhere in Gondwana, the presence of the ichnotaxon Dimetropus in the Permian of Morocco suggests the future discovery of basal synapsids (including caseids) in the Permian basins of North Africa, which were also part of the paleoequatorial belt and constituted one of the main migratory routes between the Northern and Southern Hemispheres. Phylogeny The family Caseidae was erected by Samuel Wendell Williston in 1911. In 1940, Alfred Sherwood Romer and L.W. Price placed Caseidae and Edaphosauridae in the same suborder, which they named Edaphosauria. This group is now abandoned, the edaphosaurids being closer to the Sphenacodontia (with which they form the clade Sphenacomorpha) than to the caseids. The latter are grouped with the Eothyrididae in the clade Caseasauria, which represent the most basal synapsids. The first phylogenetic analysis of caseids was published in 2008 by Hillary C. Maddin and colleagues. In this analysis, the genus Oromycter occupies the most basal position within the clade. Ennatosaurus is the sister group of a clade containing Cotylorhynchus romeri and Angelosaurus dolani. This analysis reveals for the first time the paraphyly of the genus Casea, the species “Casea” rutena representing a distinct genus which will be named in 2011