The upper Pleistocene mammal record from Caverna degli Orsi (San Dorligo della Valle – Dolina, Trieste, Italy): A faunal complex between eastern and western Europe

Abstract

Caverna degli Orsi is located near S. Dorligo della Valle – Dolina in the Trieste Karst (NE Italy), at 360 m a.s.l. on the western slope of Monte Carso in Rosandra valley. The cave is tunnel-shaped, and the original access is at present completely buried by a debrisfall deposit that covers a wide area of the mountain side. Since the cave entrance closed, sedimentation rate and weathering processes have been very low inside the cave. Therefore, a paleosurface has been preserved with minor changes. Typical traces of the presence of Ursus spelaeus are evident on the floor surface and on the walls. Two excavation sondages were carried out by the Department of Archaeological Sciences of Pisa University between 1992 and 2006. Sondage A is the inner one, while sondage B is situated in the outer part of the cave, where the tunnel entrance is obstructed by a debrisfall coming from the slope. The results of the faunal analysis, related to the possible connections with the faunal assemblages of Eastern Europe, are presented. Both stratigraphic sequences start from a flowstone, not dated but reputedly assigned to Eemian (MIS 5e). In the lowest layers of sondage B there are large mammals with warm indicators such as cf. Stephanorhinus kirchbergensis and Dama sp., in an association dominated by U. spelaeus. Among small mammals, common vole (Microtus arvalis) is dominant in both sequences. The presence of Dama sp. in the lowest levels, together with the assemblage of small mammals and stratigraphic considerations, allow a calibration of the two sequences from MIS 5 to MIS 2 (Late Pleistocene). In both sondages 26 taxa of small mammals and 24 ones of large mammals have been found. The high biodiversity in the small mammal assemblage and the occurrence of Dinaromys bogdanovi, Balkan snow vole, together with Chionomys nivalis and northern and eastern European species, such as Microtus oeconomus, Sicista betulina, Cricetulus migratorius and Mesocricetus cf. newtoni mixed together with western ones confirms the presence in this geographical area of an ecotone, with Balkan and Western Mediterranean Europe biocoenoses in the Late Pleistocene.