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Pre-print: Calandra_etal_SSFA_PCIarchaeo_revised_formatted_SI.pdf The figures are incorporated into the text but are additionally available as separate PDF files. The Supplementary Information is added at the end of the pre-print. See also related identifiers for the other supplementary materials. Figure_PCIwebsite.pdf is the thumbnail/illustration image for your article on the PCi Archaeology website. Version recommended by PCI Archaeology (see 10.24072/pci.archaeo.100024).

In mammals, complex dental microwear textures (DMT) representing differently sized and shaped enamel lesions overlaying each other have traditionally been associated with the seeds and kernels in frugivorous diets, as well as with sclerotized insect cuticles. Recently, this notion has been challenged by field observations as well as in vitro experimental data. It remains unclear to what extent each food item contributes to the complexity level and is reflected by the surface texture of the respective tooth position along the molar tooth row. To clarify the potential of seeds and other abrasive dietary items to cause complex microwear textures, we conducted a controlled feeding experiment with rats. Six individual rats each received either a vegetable mix, a fruit mix, a seed mix, whole crickets, whole black soldier fly larvae, or whole day-old-chicks. These diets were subjected to material testing to obtain mechanical properties, such as Young’s modulus, yield strength, and food hardness (as indicated by texture profile analysis [TPA] tests). Seeds and crickets caused the highest surface complexity. The fruit mix, seed mix, and crickets caused the deepest wear features. Moreover, several diets resulted in an increasing wear gradient from the first to the second molar, suggesting that increasing bite force along the tooth row affects dental wear in rats on these diets. Mechanical properties of the diets showed different correlations with DMT obtained for the first and second molars. The first molar wear was mostly correlated with maximum TPA hardness, while the second molar wear was strongly correlated with maximum yield stress, mean TPA hardness, and maximum TPA hardness. This indicates a complex relationship between chewing mechanics, food mechanical properties, and observed DMT. Our results show that, in rats, seeds are the main cause of complex microwear textures but that hard insect body parts can also cause high complexity. However, the similarity in parameter values of surface textures resulting from seed and cricket consumption did not allow differentiation between these two diets in our experimental approach.

Hypselodont (ever-growing) teeth of lagomorphs or rodents have higher wear rates (of a magnitude of mm/week), with compensating growth rates, compared to the non-ever-growing teeth of ungulates (with a magnitude of mm/year). Whether this is due to a fundamental difference in enamel hardness has not been investigated so far. We prepared enamel samples (n = 120 per species) from incisors of cattle (Bos primigenius taurus) and nutria (Myocastor coypus, hypselodont incisors) taken at slaughterhouses, and submitted them to indentation hardness testing. Subsequently, samples were split into 4 groups per species (n = 24 per species and group) that were assessed for abrasion susceptibility by a standardized brush test with a control (no added abrasives) and three treatment groups (using fine silt at 4 ±1 μm particle size, volcanic ash at 96 ±9 μm, or fine sand at 166 ±15 μm as abrasives), in which enamel abrasion was quantified as height loss by before-and-after profilometry. The difference in enamel hardness between the species was highly significant, with nutria enamel achieving 78% of the hardness of cattle enamel. In the control and the fine sand group, no enamel height loss was evident, which was attributed to thein vitrosystem in the latter group, where the sand particles were brushed out of the test slurry by the brushes’ bristles. For fine silt and volcanic ash, nutria enamel significantly lost 3.65 and 3.52 times more height than cattle. These results suggest a relationship between enamel hardness and susceptibility to abrasion. However, neither the pattern within the species nor across the species indicated a monotonous relationship between hardness and height loss; rather, the difference was due to qualitative step related to species. Hence, additional factors not measured in this study must be responsible for the differences in the enamel’s susceptibility to abrasion. While thein vitrobrush system cannot be used to rank abrasive test substances in terms of their abrasiveness, it can differentiate abrasion susceptibility in dental tissue of different animal species. The results caution against considering enamel wear as a similar process across mammals.

Pre-print: Calandra_etal_SSFA_PCIarchaeo.pdf Supplementary Material: Bayesian-models_PCIarchaeo.pdf and Comparison-analyses_PCIarchaeo.pdf See also related identifiers for the other supplementary materials. Submitted to PCI Archaeology.

Pre-print of the manuscript "Dental microwear texture analysis in Toothfrax and MountainsMap® SSFA module: Different software packages, different results?" Submitted to PCI Paleontology. See related identifiers for the associated supplementary materials.

Supplemental material, sj-pdf-1-lan-10.1177_00236772211036572 for Use of running plates by floor housed rats: A pilot study by Jessica Frei, Marcus Clauss, Daniela E Winkler, Thomas Tütken and Louise F Martin in Laboratory Animals

Strontium isotopes in biogenic apatite, especially enamel, are widely employed to determine provenance and track migration in palaeontology and archaeology. Body tissues record the 87Sr/86Sr of bioavailable Sr of ingested food and water. To identify non-local individuals, knowledge of the 87Sr/86Sr of a non-migratory population is required. However, varying factors such as tissue turnover rates, feeding selectivity, Sr content, digestibility of food, and the ingestion of mineral dust can influence body tissue 87Sr/86Sr. To evaluate the Sr contribution of diet and water to mammalian hard tissues 87Sr/86Sr, controlled feeding studies are necessary. Here we present 87Sr/86Sr from controlled feeding experiments with two rodent species (Rattus norvegicus, Cavia porcellus). Due to the continuous and fast incremental growth of rat and guinea pig incisors (∼0.1 – 0.5 mm/day), their enamel is expected to record isotopic dietary changes. For Experiment-1: Diet Switch, animals were switched from their respective supplier food to a pelleted experimental diet containing either insect-, plant-, or meat-meal and a staggered-sampling approach was used to monitor the 87Sr/86Sr changes in rat incisor enamel and bone over the course of the experiment. In Experiment-2: Basic Diets, separated cohorts (n = 6) of rats and guinea pigs were fed one of the three pelleted diets and received tap water for 54 days. While the rat incisors showed a complete tissue turnover, the slower-growing guinea pig incisors partially retained supplier diet-related isotopic compositions. In addition, one group of rats fed plant-meal pellets received Sr-rich mineral water, demonstrating that drinking water can be an important Sr source in addition to diet. Additionally, a leaching experiment showed that only a small fraction of diet-related Sr is bioavailable. Finally, in Experiment-3: Dust Addition, guinea pigs were fed pellets with and without addition of 4% of isotopically distinct dust (loess or kaolin). Animals that received kaolin-containing pellets displayed increased enamel 87Sr/86Sr. Intra-population 87Sr/86Sr variability within each feeding group was small and thus we conclude that it should not affect interpretations of 87Sr/86Sr in provenance studies. However, the differences between bulk food and leachate 87Sr/86Sr highlight the importance of Sr bioavailability for provenance studies and Sr isoscapes.

Variability of dental microwear along the tooth row, dietary data and information on specimens, statistics, parameter description, PCA details

One reason for the mammalian clade’s success is the evolutionary diversity of their teeth. In herbivores, this is represented by high‐crowned teeth evolved to compensate for wear caused by dietary abrasives like phytoliths and grit. Exactly how dietary abrasives wear teeth is still not understood completely. We fed four different pelleted diets of increasing abrasiveness (L: Lucerne; G: grass; GR: grass and rice husks; GRS: grass, rice husks, and sand) to four groups of a total of 28 adult goats, all with completely erupted third molars, over a six‐month period. Tooth morphology was captured by medical computed tomography scans at the beginning and end of the controlled feeding experiment, and separation lines between the crown and root segments were defined in the upper right second molar (M2), to gauge absolute wear. Using bootstrapping, significant differences in volume loss between diets L/G and GR/GRS were detected. A small but nevertheless consistent volume gain was noted in the roots, and there was a significant, positive correlation between crown volume loss and root volume gain. This growth could possibly be attributed to the well‐known process of cementum deposition and its relation with a putative feedback mechanism, in place to attenuate wear caused by abrasive diets.

Dental mesowear is applied as a proxy to determine the general diet of mammalian herbivores based on tooth-cusp shape and occlusal relief. Low, blunt cusps are considered typical of grazers and high, sharp cusps typical of browsers. However, how internal or external abrasives impact mesowear, and the time frame the wear signature takes to develop, still need to be explored. Four different pelleted diets of increasing abrasiveness (lucerne, grass, grass and rice husks, and grass, rice husks and sand) were fed to four groups of a total of 28 adult goats in a controlled feeding experiment over a 6-month period. Tooth morphology was captured by medical CT scans at the beginning and end of the experiment. These scans, as well as the crania obtained post mortem, were scored using the mesowear method. Comparisons between diet groups showed few significant differences after 6 months, irrespective of whether CT scans or the real teeth were scored. Only when assessing the difference in signal between the beginning and the end of the experiment did relevant, significant diet-specific effects emerge. Diets containing lower phytolith content caused a more pronounced change in mesowear towards sharper cusps/higher reliefs, while the feed containing sand did not result in more extreme changes in mesowear when compared with the same feed without sand. Our experiment suggests that the formation of a stable and hence reliable mesowear signal requires more time to develop than 6 months.