Estudio sistemático y bioestratigráfico de los Eomyidae (Rodentia) del Oligoceno superior y Mioceno inferior español = Taxonomy and biostratigraphy of Eomyidae (Rodentia) from the upper Oligocene and lower Miocene of Spain (1987)

This paper is the first fundamental study on Spanish Eomyidae. The flourishing time of this family in Europe was the Late Oligocene and Early Miocene. Four genera are recognized in this time span: Rhodanomys Deperet & Douxami, 1902, Ritteneria Stehlin & Schaub, 1951, Pseudotheridomys Schlosser, 1926, and Ligerimys Stehlin & Schaub,1951. The study is based on more than 8000 dental elements from 32 localities, which are situated in the following basins: Ebro Basin (provinces of La Rioja and Huesca), Almazan Basin (province of Zaragoza), Calatayud-Teruel Basin (provinces of Zaragoza and Teruel), Loranca Basin (province of Cuenca), and the Bunol Basin (province of Valencia). The following, anteriorly described species are recognized: Rhodanomys transiens Hugueney, 1969, Rh. schlosseri Deperet & Douxami, 1902; Ritteneria manca Stehlin & Schaub, 1951; Pseudotheridomys schaubi Lavocat, 1951, P. parvulus (Schlosser, 1884), P. fejfari Alvarez & Daams, 1987; Ligerimys antiquus Fahlbusch, 1970, L. florancei Stehlin & Schaub, 1951, L. ellipticus Daams, 1976. Seven new species are described: Rhodanomys oscensis sp. nov.; Ritteneria molinae sp. nov.; Pseudotheridomys lacombai sp. nov.; Ligerimys freudenthali sp. nov., L. fahlbuschi sp. nov., L. magnus sp. nov., L. palomae sp. nov. The evolutionary lineage of Rhodanomys transiens - Rhodanomys schlosseri - Rhodanomys oscensis - Ritteneria molinae - Ritteneria manca is characterized by a simplification of the dental pattern and a reduction of size. The biochronological value of this lineage for the Late Oligocene and Early Miocene is confirmed, and a subdivision of this time interval is made on the basis of the various evolutionary stages. Zone W is characterized by Rhodanomys transiens, zone X by Rhodanomys schlosseri and Rhodanomys oscensis, zone Yl by Ritteneria molinae, and zone Y2 by Ritteneria manca. Fahlbusch (1970) proposed the following phylogenetic model for the Pseudotheridomys - Ligerimys group: Pseudotheridomys parvulus - Pseudotheridomys-Ligerimys transitional assemblages - Ligerimys antiquus - Ligerimys florancei. We think, on the contrary, that two lineages are present in the German material. On the one hand there is a lineage composed of P. parvulus - L. antiquus - L. florancei, characterized by a simplification of the dental pattern and size increase. On the other hand, parallel to this lineage, P. parvulus continues without any apparent changes during the Early Miocene. For that matter P. parvulus is is not considered to be a good biochronological marker for MN zone 2, as it has been found in localities as high as zone MN 4 (Alvarez, Daams & van der Meulen, 1987). In Spain we propose the lineage Pseudotheridomys schaubi - P. parvulus - P. lacombai - Ligerimys antiquus - L. palomae, characterized also by a simplification of the dental pattern, and - contrary to the German situation - by a size decrease. Concurrently, during the early Miocene there is a second lineage, represented by Pseudotheridomys fejfari, characterized by a stable morphology and size increase. Considerable fluctuations are observed in the relative frequency of Eomyidae during the Late Oligocene and the Early Miocene. These fluctuations are attributed to ecological changes. A high frequency of Ligerimys appears to indicate a relatively humid environment. Se ha realizado por primera vez en Espana una revision de la familia Eomyidae, abordandose el estudio de los representantes espanoles en el periodo de mayor abundância e importância de la familia en Europa (Oligoceno superior - Mioceno inferior). Cuatro generos estan representados para este intervalo: Rhodanomys Deperet & Douxami, 1902, Ritteneria Stehlin & Schaub, 1951, Pseudotheridomys Schlosser, 1926, and Ligerimys Stehlin & Schaub, 1951. Despues dei estudio sistematico dei material de 32 localidades, que han proporcionado mas de 8.000 piezas dentarias, se han determinado las siguientes especies: Rhodanomys transiens Hugueney, 1969, Rh. schlosseri Deperet & Douxami, 1902, Rh. oscensis sp. nov.; Ritteneria molinae sp. nov., R. manca Stehlin & Schaub, 1951; Pseudotheridomys schaubi Lavocat, 1951, P. parvulus (Schlosser, 1884), P. lacombai sp. nov., P. fejfari Alvarez & Daams, 1987; Ligerimys antiquus Fahlbusch, 1970, L. freudenthali sp. nov., L. fahlbuschi sp. nov., L. magnus sp. nov., L. palomae sp. nov., L. florancei Stehlin & Schaub, 1951, L. ellipticus Daams, 1976. En determinados casos se han establecido las hipoteticas relaciones filogeneticas entre los distintos taxones diferenciados. Tambien se ha podido constatar el valor biocronologico de la linea Rhodanomys - Ritteneria y se han precisado, para Espana, los rangos y distribuciones estratigraficos de las especies estudiadas.