Primeros datos paleontológicos del sector occidental de la Cuenca de Madrid: nuevos yacimientos de microvertebrados del Oligoceno en Talavera de la Reina (prov. Toledo)

Abstract

We discovered five new sites with microvertebrates in the western sector of the Madrid Basin, the first found in the area of Talavera de la Reina, that are from the bottom to the top: Aritosa, Cantera de Talavera 1, Cantera de Talavera, Cerro Negro and La Cueva. Its Upper Oligocene age allows to date the lower arcosic unit (MI), three section, of Martin Escorza (1974) in which they appear. In some of these sites we have determined the evolution line: Zssiodoromys paufiensis - Zssiodorornys quercyi that allows us to corroborate its tendendy towards hypsodonty and also to place biostratigraphically with accuracy the sites, respectively, between the MP 26 and MP 27 units, after Schmidt-Kittler (1987) (Cantera de Talavera 1 and Cantera de Talavera) and in the MP 27 unit (Cerro Negro). Moreover, in some of these fauna1 associations we have found another Theridomyidae which belongs to the genera Archaeomys, an Sciuridae, some Cricetidae, one at least belonging to the species Eucricetodon dubius, two species of Eomyidae: Eomys cf. major and Eomys zitteli, (in which we can estimate its tendency towards the increasing size of its successive populations) and an Artyodactyla, Caenotherium sp., of great size. The composition of these fauna1 associations, in which the Theridomyidae are predominant, suggests relatively arid climatic conditions for that age in the area. Furthermore, the presence of two highly hypsodont taxa of Theridomyidae, together with some Cricetidae, and the lack of Gliridae, suggests an open environment