Aurélien Royer

Investigating the influence of climate changes on rodent communities at a regional-scale (MIS 1-3, southwestern France).

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.

Rabbits in the grave! Consequences of bioturbation on the Neandertal “burial” at Regourdou (Montignac-sur-Vézère, Dordogne)

The understanding of Neanderthal societies, both with regard to their funerary behaviors and their subsistence activities, is hotly debated. Old excavations and a lack of taphonomic context are often factors that limit our ability to address these questions. To better appreciate the exact nature of what is potentially the oldest burial in Western Europe, Regourdou (Montignac-sur-Vézère, Dordogne), and to better understand the taphonomy of this site excavated more than 50 years ago, we report in this contribution a study of the most abundant animals throughout its stratigraphy: the European rabbit (Oryctolagus cuniculus). In addition to questions surrounding the potential bioturbation of the sites stratigraphy, analysis of the Regourdou rabbits could provide new information on Neandertal subsistence behavior. The mortality profile, skeletal-part representation, breakage patterns, surface modification, and comparison with modern reference collections supports the hypothesis that the Regourdou rabbit remains were primarily accumulated due to natural (attritional) mortality. Radiocarbon dates performed directly on the rabbit remains give ages ranging within the second half of Marine Isotope Stage 3, notably younger than the regional Mousterian period. We posit that rabbits dug their burrows within Regourdous sedimentological filling, likely inhabiting the site after it was filled. The impact of rabbit activity now brings into question both the reliability of the archaeostratigraphy of the site and the paleoenvironmental reconstructions previously proposed for it, and suggests rabbits may have played a role in the distribution of the Neandertal skeletal remains.

Seasonal Insectivory of the Antillean Fruit-Eating Bat (Brachyphylla cavernarum)

Abstract. This paper reports seasonal variations in the insect component of the Antillean fruit-eating bat (Brachyphylla cavernarum) diet based on the study of guano from a colony on Guadeloupe. Fecal pellet content reveals that insects, mainly phytophagous scarab beetles (Coleoptera: Scarabaeoidea), can form an important part of Antillean fruit-eating bat feeding patterns, primarily at the beginning of the dry season.

Carbon, nitrogen and oxygen isotope fractionation during food cooking: Implications for the interpretation of the fossil human record

OBJECTIVES Stable isotope data provide insight into the reconstruction of ancient human diet. However, cooking may alter the original stable isotope compositions of food due to losses and modifications of biochemical and water components. METHODS To address this issue, carbon, nitrogen and oxygen isotope ratios were measured on meat aliquots sampled from various animals such as pork, beef, duck and chicken, and also from the flesh of fishes such as salmon, European seabass, European pilchard, sole, gilt-head bream, and tuna. For each specimen, three pieces were cooked according to the three most commonly-known cooking practices: boiling, frying and roasting on a barbecue. RESULTS Our data show that cooking produced isotopic shifts up to 1.8‰, 3.5‰, and 5.2‰ for δ13 C, δ15 N, and δ18 O values, respectively. Such variations between raw and cooked food are much greater than previously estimated in the literature; they are more sensitive to the type of food rather than to the cooking process itself, except in the case of boiling. CONCLUSIONS Reconstructions of paleodietary may thus suffer slight bias in cases of populations with undiversified diets that are restrained toward a specific raw or cooked product, or using a specific cooking mode. In cases of oxygen isotope compositions from skeletal remains (bones, teeth), they not only constitute a valuable proxy for reconstructing past climatic conditions, but they could also be used to improve our knowledge of past human diet.

Tsunami sedimentary deposits of Crete records climate during the ‘Minoan Warming Period' (≈3350 yr BP)

Earthquakes or explosive eruptions generate tsunami, which are at the origin of thick and chaotic coastal sediments. These commonly fossiliferous deposits are formed instantaneously at the historical or geological timescale and therefore have the potential to provide snapshot records of past climates. In Crete, near the city of Palaikastro, crops out a 1- to 9-m-thick sedimentary layer deposited by a huge tsunami that has been previously estimated to be about 9 m high. The presence of volcanic ash, the geometry, the archeological and faunal contents of the sedimentary deposit along with radiocarbon dating converge for interpreting this tsunamite as coeval with the Minoan Santorini (Thera) eruption ≈3350 yr BP. During its drawback, the tsunami deposited rocky blocks and a muddy matrix containing mollusc shells dredged from the seabed as well as cattle skeletal remains and various artifacts belonging to the contemporaneous Minoan civilization. While the oxygen isotope compositions of terrestrial vertebrate bone remains most likely resulted from diagenetic alteration, those of a bovid tooth revealed that air temperatures during MM3 and LM1 periods were about 4°C higher than nowadays. Oxygen isotope measurements of marine mollusc shells also revealed that sea surface temperatures were higher by about 2°C. Those results compare with the 2.5°C temperature difference already estimated according to both δ2H and δ18O values of Greenland ice cores. Incremental sampling of marine gastropods and bovid teeth suggests that the seasonal amplitude was similar to that prevailing during the second half of the 20th century.

Record of Nile seasonality in Nubian neonates.

ABSTRACT The oxygen isotope compositions of bones (n = 11) and teeth (n = 20) from 12 Sudanese individuals buried on Sai Island (Nubia) were analysed to investigate the registration of the evolution of the Nile environment from 3700 to 500 years BP and the potential effects of ontogeny on the oxygen isotope ratios. The isotopic compositions were converted into the composition of drinking water, ultimately originating from the Nile. δ18O values decrease during ontogeny; this is mainly related to breastfeeding and physiology. Those of neonates present very large variations. Neonates have a very high bone turnover and are thus able to record seasonal δ18O variations of the Nile waters. These variations followed a pattern very similar to the present one. Nile δ18O values increased from 1.4 to 4.4 ‰ (Vienna Standard Mean Ocean Water) from the Classic Kerma (∼3500 BP) through the Christian period (∼1000 BP), traducing a progressive drying of Northeast Africa.