Terrestrial ecosystems have continuously evolved throughout the Late Pleistocene and the Holocene, deeply affected by both progressive environmental and climatic modifications, as well as by abrupt and large climatic changes such as the Heinrich or Dansgaard-Oeschger events. Yet, the impacts of these different events on terrestrial mammalian communities are poorly known, as is the role played by potential refugia on geographical species distributions. This study examines community changes in rodents of southwestern France between 50 and 10 ky BP by integrating 94 dated faunal assemblages coming from 37 archaeological sites. This work reveals that faunal distributions were modified in response to abrupt and brief climatic events, such as Heinrich events, without actually modifying the rodent community on a regional scale. However, the succession of events which operated between the Late Pleistocene and the Holocene gradually led to establishing a new rodent community at the regional scale, with intermediate communities occurring between the Bølling and the Allerød.

Accurate species identification in fossil remains is a complex task but is a key component for developing good inferences on many, if not all, fundamental questions in macroecology and macroevolution. In the Quaternary, arvicolines are very abundant remains in archeological and paleontological sites in Western Europe and their identification is often based on the first lower molar. The common vole Microtus arvalis (Pallas, 1778) and the field vole Microtus agrestis (Linnaeus, 1761) are commonly found in those deposits. These two species are genetically and ecologically divergent. Nonetheless, their lower molars, on which species identification is done, exhibit a large morphological variation that can potentially lead to some confusion and misinterpretation. Moreover, molecular data suggest that present-day M. agrestis populations are a complex of divergent lineages, some of them being recognized nowadays as valid species. On the basis of extant populations representing a large part of the present-day geographical distribution of these two species, we developed a classification model based on geometric morphometrics of the first lower molar. Our statistical model was then applied on four fossil sites selected to evaluate the relevance of taxonomic determination found in species lists. The model using landmarks describing the overall shape of the first lower molar classifies the two species with the smallest prediction error together with very high individual posterior probabilities. The obtained classification is much better than those arising from shapes of any specific molar part such as the anterior loop, asymmetry or peculiar triangle shape. Discrepancies with expert classification on fossils suggest that existing faunal lists should always be considered cautiously for these two species. Our morphometric model provides a first step towards a rationalized way of revising past collections and expertise for future small mammal assemblages. It will thus help us better understand the paleobiogeographical expansion of these two key species in Quaternary faunas.

In order to track diachronic changes in archaeological sequences, researchers typically partition time into stratigraphic layers defined during fieldwork, which serve as the framework for ensuing analyses. These analytical units have a significant impact on archaeological inference, defining its resolution, and influencing both the study of cultural assemblages and the reconstruction of past environments. However, field layers are seldom re-evaluated after excavation despite the fact that archaeological deposits are now commonly recognised as often containing material ‘mixed’ together by site formation processes, excavation techniques, or analytical practices. Although the analysis of intra-site spatial data clearly offers a means to overcome these issues, our literature review of 192 journal articles revealed the potential of this data (notably vertical projections of piece-plotted artefacts) to be under-exploited in prehistoric archaeology. Here, we advocate for the development of a more spatially informed framework for interpretation that we refer to as post-excavation stratigraphy or PES. After proposing a definition for PES, we attempt to develop a framework for theoretical considerations underlying their implication, importance, and potential. Three main benefits of PES are highlighted: ensuring assemblage reliability, increased chronological and spatial resolution, and more reliable interpretations based on a multi-stratigraphic approach. We contend that the stratigraphy defined during fieldwork is insufficient and potentially misleading. By providing a different “stratigraphic view” of the same sequence, each specialist can contribute data that, when combined, produces a better understanding of interactions between changes in, for example, technological or cultural traditions, subsistence strategies, or paleoenvironments.

The narrow-headed vole, collared lemming and common vole were the most abundant small mammal species across the Eurasian Late Pleistocene steppe-tundra environment. Previous ancient DNA studies of the collared lemming and common vole have revealed dynamic population histories shaped by climatic fluctuations. To investigate the extent to which species with similar adaptations share common evolutionary histories, we generated a dataset comprised the mitochondrial genomes of 139 ancient and 6 modern narrow-headed voles from several sites across Europe and northwestern Asia covering approximately the last 100 thousand years (kyr). We inferred Bayesian time-aware phylogenies using 11 radiocarbon-dated samples to calibrate the molecular clock. Divergence of the main mtDNA lineages across the three species occurred during marine isotope stages (MIS) 7 and MIS 5, suggesting a common response of species adapted to open habitat during interglacials. We identified several time-structured mtDNA lineages in European narrow-headed vole, suggesting lineage turnover. The timing of some of these turnovers was synchronous across the three species, allowing us to identify the main drivers of the Late Pleistocene dynamics of steppe- and cold-adapted species.