Résumé
L’opportunité de traiter un plus grand nombre de blocs du site karstique pliocène terminal de Mas Rambault 2 a permis de compléter le registre fossile de cette localité concernant les rongeurs ainsi que les insectivores et les chiroptères. La liste initiale de rongeurs fournie par B. Bachelet (1990) s’enrichit de 4 taxons : deux gliridés, Eliomys intermedius, Glis sackdillingensis, et deux muridés Apodemus cf. jeanteti et Micromys praeminutus ce qui porte le nombre de rongeurs à 11 espèces. Les insectivores représentés par 9 taxons et les chiroptères par 12, sont décrits pour la première fois. Ce niveau est actuellement le plus récent du Pliocène du Sud de la France. Cette microfaune témoigne d’un climat encore relativement chaud avec peut-être une saisonnalité plus marquée pour la période fini-pliocène. La datation de plusieurs sites karstiques sur le pourtour du Bassin de Thau sont intégrés à des travaux concernant la géodynamique et la géomorphologie régionale.
Mots-clés : Rodentia, Insectivora, Chiroptera, Pliocène sup., Paléoclimat, Remplissage karstique, Hérault
Abstract
An enlarged matrix sample collected from the Late Pliocene Mas Rambault 2 karstic fill, near Montpellier, France, contains an enriched faunal assemblage with respect to rodents as well as insectivores and bats. Four additional rodent taxa (two glirids: Eliomys intermedius and Glis sackdillingensis; and two murids: Apodemus cf. jeanteti and Micromys praeminutus), nine insectivore taxa and twelve bats not previously recognized from this site have been identified. The faunal composition and evolutionary stage of some rodent species (Stephanomys, Castillomys) indicate a slightly younger age than those from localities at Seynes, Ségriès, Balaruc 6, Lo Fournas 4, Grand Serre (Aguilar et al., 1993), and a slightly older age than those from Balaruc 1 and Mas Rambault 1, where the vole Microtus (Allophaiomys) pliocaenicus is found, as well as those from Valensolette. All of these localities are in southern France. According to the current mammalian biochronology of the European Plio-Pleistocene and to available magnetostratigraphic correlation of a few southern France faunas, the Mas Rambault 2 fill could have been deposited during a time interval between 2.2 and 1.6 Ma. The Mas Rambault 2 locality actually documents the youngest Pliocene level recognized to date in southern France. The small mammals from Mas Rambault 2 indicate rather subtropical climatic conditions. Warm temperatures are suggested by the murid Stephanomys, a still dominant element among Pliocene rodent faunas. The bat fauna contains such genera as Megaderma and Hipposideros whose extant representatives are tropical, and which were already members of the warmer, subtropical, Pliocene faunas (Aguilar et al., 1999). A similar conclusion may be drawn from the leuconoform vespertilionines, which suggests a closer relationships to extant tropical representatives than to palaeoarctic ones. Among the insectivores, the combined occurrence of a single crocidurine species, of various soricines, and of Sorex minutus (a taxon currently absent from the Mediterranean borders) may nevertheless suggest somewhat colder conditions, or at least a broader seasonal temperature range. The chronological information yielded by the Mas Rambault 2 locality, as well as by other fossiliferous fissure fills studied in the area, together with data taken from the geological literature (journals, geological reports) is tentatively utilized here to contribute to a regional interpretation of the geodynamics of the area and its geomorphological evolution. Several aspects of the geological history of the area are subsequently discussed or re-examined.
Key words: Rodentia, Insectivora, Chiroptera, Upper Pliocene, Paleoclimate, Karst filling, Hérault France
Dernière mise à jour le 02.07.2015