Rationale Embedding resins are commonly used to facilitate high‐resolution sampling for stable isotope analysis but anomalous δ13C values have been observed in some cases. Here we compare the results of microsampling strategies for hand‐drilled versus resin‐embedded micromilled samples from the same marine shells to assess whether resin contamination is implicated in δ13C spikes. The comparison allows assessment of the relative benefits for spatial resolution, seasonal range for both δ18O and δ13C, and sample failure rates. Methods Hand‐drilled samples were obtained from two bivalve shells (Spisula sachalinensis), corresponding to micromilled samples on the same shells where high δ13C spikes were observed. All carbonate powders were analysed using a dual‐inlet Isoprime mass spectrometer and Multiprep device. Results from both sample sets were compared statistically. Results No anomalous high δ13C values and no failures due to insufficient gas were observed in the hand‐drilled samples in contrast to the embedded micromilled sequences. Spatial resolution was reduced (~2.5×) in the former compared with the latter, resulting in a small reduction in the total range observed in the micromilled δ13C and δ18O values. Reduced sampling resolution between the two datasets was only significant for δ18O. Conclusions For S. sachalinensis (as with other similar bivalves), rapid growth mitigates the reduced sampling resolution of hand drilling and does not significantly impact observed isotopic range and seasonal patterning. Occurrence of anomalous δ13C values were eliminated and failure rates due to insufficient sample size greatly reduced in the hand‐drilled dataset. We can find no other explanation for the occurrence of δ13C spikes than contamination by the embedding agent. We conclude that the logistical and interpretational benefits of careful hand drilling may be preferable to resin embedding for micromilling in marine shells, corals or speleothems where growth rate is rapid and the highest resolution is not required.

The Mesolithic-Neolithic transition is a classic topic of archaeological discussion, and the East Adriatic is of particular interest as a gateway region for agriculture entering Europe from the Near East. Neolithisation along the East Adriatic coast has been characterised as a two-wave process of leap-frog demographic replacement along the Dalmatian coast, followed by a longer process of acculturation further inland. Research on this transition primarily addresses the arrival of Neolithic technology and domesticates, but the view from 'traditionally Mesolithic' activities can provide an alternative perspective.This pilot study highlights one such practice, identifying changes in the seasonality of shellfish gathering over the Neolithic transition using material from Vela Spila, Korčula (Croatia). Specimens of the gastropod Phorcus turbinatus from across this transition were assessed using oxygen isotope analysis. Results showed a focus on summer and autumn collection during the Mesolithic, which then shifted to autumn and winter in the Neolithic. These results indicate differences in shellfish gathering and exploitation across the Neolithic transition, and implications for the demographic transition and humanenvironment interactions are discussed. Shellfishing in the East Adriatic is identified as an area of Neolithisation rather than Mesolithic continuity.

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