Early-middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy)

This paper compares stable isotope (δ<sup>18</sup>O and δ<sup>13</sup>C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ<sup>18</sup>O (δ<sup>18</sup>Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ<sup>13</sup>C (δ<sup>13</sup>Cs) variability was significant, probably due to different feeding behaviour among species. The δ<sup>18</sup>Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of <sup>18</sup>O-depleted winter rainfall in their δ<sup>18</sup>Os is lost. This suggests that δ<sup>18</sup>Os and δ<sup>13</sup>Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ<sup>18</sup>Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ<sup>13</sup>Cs trend suggests a transition from a slightly <sup>13</sup>C-enriched to a <sup>13</sup>C-depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ<sup>13</sup>Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO<sub>2</sub> concentration