Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>An assemblage of the early Miocene <jats:italic>Sayimys giganteus</jats:italic> (Ctenodactylinae, Rodentia) from its type locality Keseköy, and smaller assemblages of Yapıntı and Horlak (Anatolia, Turkey) are described. Almost all <jats:italic>Sayimys</jats:italic> species are known from small collections of isolated cheek teeth. The very large assemblage from Keseköy is of special interest, because it allows the study of the intra-specific variation of dental morphology: size, the morphological changes through wear and the criteria for recognition of the tooth position of molars. The results have been used to review the formally named <jats:italic>Sayimys</jats:italic> species and to evaluate the dental features used to define the species. The review of the early and middle Miocene succession of <jats:italic>Sayimys</jats:italic> in the Siwaliks (Pakistan) resulted in the resurrection of <jats:italic>S</jats:italic>. <jats:italic>minor</jats:italic>; <jats:italic>S</jats:italic>. <jats:italic>baskini</jats:italic> is considered to be a junior synonym of <jats:italic>S</jats:italic>. <jats:italic>minor</jats:italic>. <jats:italic>S</jats:italic>. <jats:italic>sivalensis</jats:italic> and <jats:italic>S</jats:italic>. <jats:italic>obliquidens</jats:italic> are nomina dubia, and restricted to their holotypes, <jats:italic>S</jats:italic>. <jats:italic>hintoni</jats:italic> n. sp. is established for mediumsized <jats:italic>Sayimys</jats:italic> from the Kamlial, lower Chinji and Manchar Formations and <jats:italic>S</jats:italic>. <jats:italic>chinjiensis</jats:italic> is resurrected for <jats:italic>Sayimys</jats:italic> from the upper Chinji and Nagri Formations. It is suggested that the middle Miocene species <jats:italic>Sayimys intermedius</jats:italic> and <jats:italic>S</jats:italic>. <jats:italic>assarrarensis</jats:italic> from Saudi Arabia are synonymous.</jats:p>