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Abstract Ground squirrels were an important member of the Pleistocene steppe-tundra mammal community. They evolved ecological specialisations and exhibit behaviours that make them particularly informative subjects to study palaeoenvironmental constraints affecting species distribution and speciation. Interspecific competition and isolating geographical barriers are considered as the principal factors that define species range boundaries. The present paper provides a first comprehensive compilation of the living and extinct Spermophilus species in Europe. These data suggest 'patchwork quilt' model for the expansion and spatial distribution of ground squirrel species. Here we consider mainly small-sized Spermophilus species because large-sized (e.g., S. superciliosus) ground squirrels consist another 'patchwork quilt', which overlap the first one. This overlapping of the species ranges is possible because of the size difference that lowers interspecific competition (Hutchinson's rule). We consider two main types of range boundaries. One type includes roughly 'sub-parallel' boundaries that oscillate in concert with climatic and vegetational changes (a case of climatically controlled competitive exclusion). The other type consists of roughly 'sub-meridional' boundaries corresponding to geographical barriers (e.g., water barriers, mountain ridges); these boundaries are rather stable. Examples of 'sub-parallel range modifications include: oscillations of boundaries between S. pygmaeus and S. suslicus ; the immigration of S. citellus into the Pre-Carpathian area; the branching of S. suslicus from S. pygmaeus ; the regional appearance of the Late Pleistocene species S. severskensis and S. citelloides. Examples of 'sub-meridional events' are: the crossing of the Danube by S. citellus ; the appearance of an isolated population of S. pygmaeus on right bank of the Dnieper during the Late Pleistocene to Middle Holocene; a crossing of the Dnieper river by S. pygmaeus , which resulted in the appearance of S. odessanus ; the intrusion of eastern populations of S. pygmaeus into the Trans-Volga areas. [ABSTRACT FROM AUTHOR]

This paper presents evidence of the discovery of a new Middle Pleistocene site in central southern England, with undisturbed evidence of hominin occupation well-dated to an interstadial towards the end of Marine Isotope Stage 8, c. 250,000 BP. The site consists of a preserved remnant of a river terrace and its alluvial floodplain overlain by chalk-rich bankside deposits, all abutting a Chalk bedrock riverbank. It preserves an area of occupation with activity focused on the riverbank, complemented by occasional activity on a palaeo-landsurface developed on the surface of the alluvial floodplain. Lithic technology at the site consists almost entirely of handaxe manufacture, allowing attribution to an Acheulian industrial tradition. Mammalian and other palaeo-environmental remains are present and associated with the occupation horizons, including large mammal bones showing signs of hominin interference. Dating was based on OSL determinations on the sediments and amino acid racemisation of molluscan remains, supported by biostratigraphic indications. Besides being a rare instance of an undisturbed Palaeolithic palaeo-landscape covering several hectares, the site contributes to wider Quaternary research concerns over the ability of Middle Pleistocene hominins to tolerate colder climatic episodes in higher latitudes, and over settlement history and changing lithic industrial traditions of northwest Europe in relation to climate change and British peninsularity. It is suggested that the Harnham evidence may represent an insular population that had persisted in southern Britain since MIS 10/9, which became locally extinct during the glacial maximum 8.2 marking the end of MIS 8. [ABSTRACT FROM AUTHOR]