The researcher Davinia Moreno, a geochronologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), is the lead author of an article published in the journal Quaternary International on the Electron Spin Resonance (ESR) dating of sediments and herbivore teeth from the Valdocarros, Maresa and Preresa sites in Madrid, which has enabled the established chronology to be refined and confirmed the oldest presence of the species Microtus cabrerae, or Cabrera‘s vole, in this region.

The site at Preresa, lying in the valley of the River Manzanares, contains this species, endemic to the Iberian Peninsula and associated to the Upper Pleistocene, in its fossil record, and it had previously been dated to 85,000 years using the method of Luminescence.

Nevertheless, the results of this work make it older, suggesting an age of around 200,000 years, that is, placing it around the end of the Middle Pleistocene. This new date obtained by ESR, applied to sedimentary quartzes and fossil teeth, indicates the oldest known presence of this rodent in the Iberian Peninsula.

With respect to the sites at Valdocarros and Maresa, lying in the valley of the River Jarama, this study suggests an age of around 300,000 years for the base of the stratigraphic sequence (level Arganda I), reaching 150,000 years at the ceiling of the sequence (level Arganda III).

“The results we’ve obtained are consistent with the datings carried out previously using the technique of Aminoacid Racemization, a chemical dating method allowing organic traces to be dated as far back as the Middle Paleolithic, and this gives us a more solid chronological framework for these Madrid sites, and the region”, states Moreno.