Kitching, James W.Raath, Michael A.2014-12-232014-12-2319840078-8554http://hdl.handle.net/10539/16130Recent intensive collecting from the Elliot Formation and lower part of the Clarens Formation of the Orange Free State is reported and a broad description is given of the general lithology of the beds in this area. Productive localities in the main Karoo basin (northeastern Cape Province, Lesotho, Orange Free State} are listed with a summary of the tetrapods recovered from each. A preliminary biozonation of these strata is proposed based on the vertical ranges of the prosauropod saurischian genera Euskelosaurus and Massospondylus. Attention is drawn to a palaeontologically rich horizon within the Massospondylus Range Zone which is designated the Tritylodon Acme-zone on the basis of the abundance in it of the advan- ced cynodont Tritylodon cf. longaevus. It is concluded that previous taxonomic work on the tetrapod fauna of these strata has resulted in an erroneous impression of faunal diversity.enEuskelosaurusMassospondylusTritylodon Acme ZoneMassospondylus range zoneArticle