Resumen de First faunal insights from biozone Db, middle Miocene, middle Aragonian, of the Madrid Basin, Spain
Verónica Hernández Ballarín, Adriana Oliver Pérez, Juan Antonio Cárdaba, María Presumido, Pablo Peláez-Campomanes de Labra
Purpose Palaeontological excavations following public works around the Manzanares River in the metropolitan area of Madrid yielded new small mammal fossil remains from two locations. We present here a description of their rodent assemblages, and a biostratigraphical and palaeoecological context of them. A comparison of these levels to the contemporaneous fossil localities of the CalatayudMontalba´n Basin and to other middle Aragonian sites from Madrid is also shown.
Material A total of 371 dental elements have been studied from the five levels of the two locations (Puente de Praga site and Madrid Rı´o2 site).
Results The rodent associations from the five new levels are similar and comprise eight taxa: Megacricetodon primitivus, Megacricetodon vandermeuleni, Democricetodon moralesi, Democricetodon sp., Armantomys aragonensis, Microdyromys koenigswaldi, Pseudodryomys ibericus and Heteroxerus rubricati. It represents a low equitable rodent community characterized by the predominance of the genus Megacricetodon and a poorly-represented fauna of glirids and sciurids.
Conclusions The fossil association and its biostratigraphical markers indicate a correlation of the levels to the upper part of biozone Db, this being the first time that the rodent assemblages of this biozone are described in the Madrid Basin. Based on the rodent content we suggest more humid or/and more closed environments in biozone Db than in biozones Dc and Dd. TheCalatayud-Montalba´n record shows more diverse rodent assemblages in biozone Db, with taxa not recorded in Madrid that are indicative of more humid or structured environments. Therefore, the Madrid associations would represent dryer or/and more open environments than the Calatayud-Montalba´n associations.
