The last appearance datum of Hipparion in Western Europe: magnetostratigraphy along the Pliocene–Pleistocene boundary in the Villarroya basin (Northern Spain)

Abstract

The Villarroya Basin in Northern Spain contains one of the classic Villafranchian localities of Europe and allows about 100 m of sediments to be explored by magnetostratigraphic techniques. Besides, the occurrence of some other macro- and micro-mammifera fossils becomes Villarroya in one of the most important Villafranchian localities of Southern Europe. Therefore, we have sampled two sections (one contains the classic locality) to shed some light on its chronostratigraphy. Detailed stepwise demagnetization has revealed primary and reliable directions (carried by magnetite and hematite) in more than 250 samples and allows us building a robust local polarity scale. The correlation with the geologic time scale locates the local sequence along the Gauss and Matuyama chrons. A Réunion chron (C2r.1n) equivalent age (2.128–2.148 Ma) is here proposed for the Villarroya fossil locality since it is clearly located above the Gauss/Matuyama boundary (very well defined in the magnetostratigraphic section) and displays normal polarity. This correlation implies a new age assignment for the classic paleontological fossil locality of Villarroya and a Last Appearance Datum of Hipparion sensu lato in Western Europe significantly younger than previously established. Taking into account this new dating, the Hipparion and Equus horses could have coexisted in Europe up to the complete extinction of Hipparion in early Matuyama times.