Palaeoecological characterization of the Pliocene-Pleistocene transition on the Mediterranean littoral area: Almenara-Casablanca (Castellón, eastern Spain)

Abstract

The Pliocene-Pleistocene transition in the Almenara region (eastern Spain) is investigated through the analysis of herpetofaunal assemblages from ACB-4 (latest Pliocene, MN16) and ACB-1 (earliest Pleistocene, MN17), serving as proxies for palaeoclimate and palaeoenvironmental reconstructions. Our study revealed the presence of new taxa not identified in previous studies in ACB-4 site (Tarentola mauritanica and Testudines indet.), thus enlarging previous faunal lists. Palaeoecological reconstructions indicate a shift from forest and scrubland dominance in the Late Pliocene to open habitats in the Early Pleistocene, potentially influenced by the onset of the double seasonality (hot and dry summers, with rainfall concentrated during the other seasons and low temperatures during winter) that characterized the Mediterranean climate then. Palaeoclimatic analyses suggest cooler and wetter conditions during this transition than currently, with higher Mean Annual Temperature (MAT) and Mean Annual Precipitation (MAP) during the earliest Pleistocene than in the latest Pliocene. Moreover, according to our results precipitations had a more seasonal character in ACB-1, which likely influenced the vegetation and habitat types in the region. The higher seasonality in ACB-1 may have played a significant role in the inferred ecological changes (shift from forest to open habitats), though other factors could also be involved. These results have been contextualized in the regional palaeoclimatic evolution during the early Quaternary by comparing them with those provided by the palaeoherpetofaunal assemblage from ACB-3 site (Early Pleistocene), according to which open habitats became increasingly dominant and a slight increase in rainfall seasonality took place compared to ACB-1. Overall, our findings contribute to a better understanding of the ecological and climatic dynamics that took place in the Pliocene-Pleistocene transition of the Almenara region, showing the importance of the integration of diverse proxies and methodological approaches for comprehensive reconstructions.