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Abstract. Plant wax n-alkane chain length distribution and δ13C have been studied in modern ecosystems as proxies to reconstruct vegetation and climate of the past. Studies on modern plants often report both chain-specific n-alkane concentrations and δ13C values. However, studies on geological archives interpret only one proxy, while both carry crucial information on the mixing sources. We propose a multi-source mixing model in a Bayesian framework that evaluates both proxies simultaneously. The model consists of priors that include user-defined source groups and their associated parametric distributions of n-alkane concentration and δ13C with well characterized uncertainties. The mixing process involves newly defined mixing fractions such as fractional leaf mass contribution (FLMC) that can be used in vegetation reconstruction, and fractional source contribution to a specific n-alkane homologue (FSCn). Markov Chain Monte Carlo is used to generate samples from the posterior distribution conditioned on both proxies. We present two case studies with distinct sets of priors. One involves n-C27, n-C29 and n-C31 alkanes in lake surface sediments of Lake Qinghai, China. The model provides more specific interpretations on the n-alkane input from aquatic sources than the conventional Paq proxy. The other involves n-C29, n-C31 and n-C33 alkanes in lake surface sediments in Cameroon, western Africa. The model produces mixing fractions of forest C3, savanna C3, and C4 plants, offering additional information on the dominant biomes compared to the traditional two-endmember mixing regime. FSCn can be used to assess the interpretation of associated n-alkane δ2H values, and future versions of the model incorporating lipid H isotope systematics could support integration of this proxy with C isotope and chain length distribution data. Despite the achievements, processes associated with n-alkane integration into sedimentary archives have not been incorporated, and the model could be further improved by adding components such as n-alkane turnover and transportation. Future studies on modern plants and catchment systems will be critical to develop calibration datasets that advance the strength and utility of the framework.

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Neogene and Pleistocene African suids displayed convergent evolutionary trends in the third molar (M3) morphology, with increasingly elongated and higher crowns through time. While these features can prevent premature loss of masticatory functionality and potentially increase long-term reproductive success, changes in dental occlusal traits such as enamel complexity and thickness can also improve chewing efficiency and increase short-term energetic return. While both long-term and short-term benefits can contribute to the thriving of a lineage, the selective pressures associated with each category can be different. To examine how crown elongation correlates with these functional occlusal traits, we selected M3s of Kolpochoerus, Notochoerus, and Metridiochoerus from Kenya and South Africa, dated between 3.0 Ma and 0.4 Ma. To account for dental wear, we used micro-computed tomography imaging of unworn/slightly worn M3s to simulate wear progression within each tooth. We compared morphometric representatives of occlusal enamel complexity and thickness among the specimens following their respective wear trajectories. We found that M3 elongation correlates with higher occlusal complexity and thinner enamel in Notochoerus and Metridiochoerus lineages through time. In Kolpochoerus, enamel complexity and thickness were generally maintained through time, despite M3 elongation. The differences in M3 morphometric trends suggest that Kolpochoerus likely experienced a different set of selective pressures on functional occlusal traits compared with Notochoerus and Metridiochoerus. The shared evolutionary trends of M3 specialization among Notochoerus and Metridiochoerus suggest similar selective pressures on their chewing efficiency and the possibility of a dietary niche overlap in more xeric habitats.

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