The Chattian flora of La Val (Estadilla, NE Spain): Taxonomic revision and implications for Oligocene vegetation

Abstract

The La Val fossil site in the northeastern Iberian Peninsula preserves a valuable record of late Oligocene (Chattian) plant communities in southern Europe. We present a revision of 1413 plant macrofossils collected between 2012 and 2017, significantly expanding previous knowledge of the site. The assemblage includes ferns, gymnosperms, and angiosperms, revealing a diverse flora dominated by riparian and mesophytic taxa. Several species, including Platanus neptuni and Ailanthus confucii, are recorded for the first time in the Iberian fossil record. Palaeobotanical and sedimentological evidence indicate the presence of vegetation adapted to warm temperate conditions with seasonal water availability, associated with alluvial fan and fluvial depositional systems. Comparisons with contemporaneous Central European floras reveal biogeographic connections across the Paratethys region during the late Oligocene. The revision of previous taxonomic assignments provides new species- level identifications and refine palaeoenvironmental interpretations of the La Val flora, improving our understanding of vegetation patterns in Europe during the Cenozoic.