Rhinocerotidae (Mammalia, Perissodactyla) from the latest Oligocene Thézels locality, SW France, with a special emphasis on Mesaceratherium gaimersheimense Heissig, 1969

Abstract

A taxonomic revision of the Rhinocerotidae from the latest Oligocene locality of Thézels in SW France is provided, based on comparative description of several hundreds of mandibular, dental, and postcranial specimens. In terms of abundance, the small-sized and slender-limbed rhinocerotine Mesaceratherium gaimersheimense Heissig, 1969 widely outnumbers the medium-sized and shorter-limbed teleoceratine Diaceratherium aff. lemanense. The material from Thézels in particular adds to the knowledge of M. gaimersheimense in providing for the first time valuable information on most elements of its appendicular skeleton, virtually unknown thus far. This work further confirms that M. gaimersheimense is restricted to the latest Oligocene interval, whereas M. paulhiacense (Richard, 1937) also first occurring in latest Oligocene deposits, survives during the earliest Miocene (Aquitanian standard age; Agenian European Land Mammal Age). The Agen area in SW France (type area of the Agenian ELMA) provides a well-documented sequence for latest Oligocene-earliest Miocene rhinocerotids of Western Europe with Thézels (MP30), Paulhiac (MN1), and Laugnac (MN2). Mesaceratherium gaimersheimense shows several postcranial differences with M. paulhiacense (shape of articular facets on central metapodials; slenderer astragalus but less slender metapodials) suggesting a still more cursorial locomotory mode for the latter species.