Ecogeographical stability and climate forcing in the Late Miocene (Vallesian) rodent record of Spain

Abstract

The composition and structure of rodent taxocenosis from three Iberian basins with a reasonably complete record (Calatayud–Teruel, Duero and Vallès–Penedès) for the latest Aragonian and Vallesian (Middle–Late Miocene) is explored using Correspondence Analysis (CA). CA classifies the assemblages in four great groups that are interpreted as rodent paleocommunity types (RPTs). On the basis of paleobotanical and paleomastological data available for some of the sites considered (or time-equivalent localities) each RPT is considered to be characteristic of certain environmental conditions. Taxonomic membership and relative abundance patterns in the recognized RPTs are quite stable throughout relatively long time intervals in each basin, suggesting the existence of coordinated stasis. However, the predictions of coordinated stasis are only partly achieved, and important differences are shown to occur within certain RPTs. RPTs with a low species richness and dominated by one or two genera characterize the record of the Duero Basin. In the case of the Vallès–Penedès and Calatayud–Teruel more equitative RPTs with a high species richness are present during the Early Vallesian (and also during the latest Aragonian in the Vallès–Penedès). The Late Vallesian sites appear as clearly differentiated of the remaining ones and grouping is strongly influenced by geographic position. The environment seems to have been more open and wet–dry seasonal in the Late Vallesian sites of the Calatayud–Teruel and Duero basins. Instead in the Vallès–Penedès Basin it appears to have been more humid and cool–warm seasonal. This fact points to the existence of a zonation of the Iberian climate during the Late Vallesian that closely matches the pattern observed today.