Biostratigraphy, palaeogeography and palaeoenvironmental significance of Sorex runtonensis Hinton, 1911 (Mammalia, Soricidae): First record from the Iberian Peninsula

• First record of Sorex runtonensis in Iberia is from Sima del Elefante (Burgos, Spain).
• Morphological and morphometrical data support the assignation.
• The specimens of Sima del Elefante display some particular Early Pleistocene traits.
• S. runtonensis is regarded as representative of tundra and steppe biotopes.
• Previous palaeoenvironmental reconstructions should be revised according to this.

Sorex runtonensis (Mammalia, Soricidae) is a well-known Pleistocene taxon with a broad distribution in Europe. However, no record of the species had been reported from the Iberian Peninsula up to now. Here we present nearly two hundred specimens of S. runtonensis recovered from the Lower Red Unit (levels TE7–14) of Sima del Elefante (Sierra de Atapuerca, Burgos, Spain), dated to ~ 1.1–1.5 Ma. Rigorous morphometrical and morphological analyses allowed the assignation of the items from Sima del Elefante confidently to this taxon, distinguishing them from the several other Pleistocene species of similar size that inhabited Europe. Sorex runtonensis survived all through the Pleistocene (and maybe more), but the remains from Sima del Elefante exhibit some traits that appear to be particular to the Early Pleistocene, which agrees with the pre-Jaramillo chronology inferred for the lower levels of the site. Western Palearctic S. runtonensis has been regarded as a proxy of patchy and relatively arid, open past biotopes due to its similarity to recent Eastern Palearctic S. tundrensis. In light of this fact, and given the high relative quantities of this taxon at the site, previous palaeoenvironmental reconstructions proposed for the lowermost unit of Sima del Elefante should be revised to present a more ecologically diverse scenario than previously thought.