Changing perspectives on early hominin diets.

It is axiomatic that knowledge of the diets of extinct hominin species is central to any understanding of their ecology and our evolution. The importance of diet in the paleontological realm has led to the employment of multiple approaches in its elucidation. Some of these have deep historical roots, while others are dependent upon more recent technical and methodological advances. Historically, studies of tooth size, shape, and structure have been the gold standard for reconstructing diet. They focus on species-level adaptations, and as such, they can set theoretical brackets for dietary capabilities within the context of specific evolutionary moments. Other methods (e.g., analyses of dental calculus, biogeochemistry, and dental microwear) have only been developed within the past few decades, but are now beginning to yield evidence of the actual foods consumed by individuals represented by fossil remains. Here we begin by looking at these more "direct" forms of evidence of diet before showing that, when used in conjunction with other techniques, these "multi-proxy" approaches can raise questions about traditional interpretations of early hominin diets and change the nature of paleobiological interpretations.

Uncovering widespread Anthropocene dietary shifts in Chinese large mammalian herbivores.

The Anthropocene's human-dominated habitat expansion endangers global biodiversity. However, large mammalian herbivores experienced few extinctions during the 20th century, hinting at potentially overlooked ecological responses of a group sensitive to global change. Using dental microwear as a proxy, we studied large herbivore dietary niches over a century across mainland China before (1880s-1910s) and after (1970s-1990s) the human population explosion. We uncovered widespread and significant shifts (interspecific microwear differences increased and intraspecific microwear dispersion expanded) within dietary niches linked to geographical areas with rapid industrialization and population growth in eastern China. By contrast, in western China, where human population growth was slower, we found no indications of shifts in herbivore dietary niches. Further regression analysis links the intensity of microwear changes to human land-use expansion. These analyses highlight dietary adjustments of large herbivores as a likely key factor in their adaptation across a century of large-scale human-driven changes.

Investigating the dietary niches of fossil Plio-Pleistocene European macaques: The case of Macaca majori Azzaroli, 1946 from Sardinia.

The genus Macaca includes medium- to large-bodied monkeys and represents one of the most diverse primate genera, also having a very large geographic range. Nowadays, wild macaque populations are found in Asia and Africa, inhabiting a wide array of habitats. Fossil macaques were also present in Europe from the Late Miocene until the Late Pleistocene. Macaques are considered ecologically flexible monkeys that exhibit highly opportunistic dietary strategies, which may have been critical to their evolutionary success. Nevertheless, available ecological information regarding fossil European species is very sparse, limiting our knowledge of their evolutionary history in this geographic area. To further our understanding of fossil European macaque ecology, we investigated the dietary ecology of Macaca majori, an insular endemic species from Sardinia. In particular, we characterized the dental capabilities and potential dietary adaptations of M. majori through dental topographic and enamel thickness analyses of two M2s from the Early Pleistocene site of Capo Figari (1.8 Ma). We also assessed its diet through dental microwear texture analysis, while the microwear texture of M. majori was also compared with microwear textures from other European fossil macaques from mainland Europe. The dental topographic and enamel thickness analyses suggest that M. majori frequently consumes hard/mechanically challenging and/or abrasive foods. The results of the dental microwear analysis are consistent with this interpretation and further suggest that M. majori probably exhibited more durophagous dietary habits than mainland Plio-Pleistocene macaques. Overall, our results indicate that M. majori probably occupied a different dietary niche compared to its mainland fossil relatives, which suggests that they may have inhabited different paleoenvironments.

Early specialized maritime and maize economies on the north coast of Peru.

We assess diet and economies of middle Holocene (∼7,500 to 4,000 calibrated [cal] B.P.) humans at coexisting mound sites (Huaca Prieta and Paredones) in north coastal Peru and document regular consumption of maize by ∼6,500 to 6,000 cal B.P. and its earliest use as a staple food in this area of the Andes between 5,000 and 4,500 cal B.P. Stable isotope data from enamel carbonates and dentin collagen (childhood diet) and dental microwear texture analysis (adult diet) demonstrate dietary and economic specialization. Previous studies revealed maize and mixed-food refuse at both sites, but this study documents actual food consumption, showing that these communities situated a few hundred meters apart had significantly distinct diets in childhood and adulthood. Huaca Prieta focused on marine resources, although there are some contributions from terrestrial meat. Paredones individuals primarily consumed maize during childhood (up to 70% of the juvenile diet), as shown by δ13C values, apatite-collagen spacing, and discriminant analysis of δ13Ccoll, δ13Ccarb, and δ15N values. Maize was likely used as a weaning food (e.g., gruel and/or chicha-a maize beverage), hinting at the significant role of breastfeeding mothers, weanling infants, and children in the development of maize as a staple crop. Additionally, dental microwear data show Paredones adult diets are high in abrasives, potentially from maize processing. The distinct foodways at these neighboring sites result from and also reflect their social and political distinctions. These differences in food production, distribution, and consumption generated opportunities for exchange, an interaction that bound them together in mutual benefit.

Feeding ecology of the last European colobine monkey, Dolichopithecus ruscinensis.

Currently, very little is known about the ecology of extinct Eurasian cercopithecids. Dietary information is crucial in understanding the ecological adaptations and diversity of extinct cercopithecids and the evolution of this family. For example, the colobine genus Dolichopithecus is represented by multiple large-bodied species that inhabited Eurasia during the Pliocene-Early Pleistocene. The available evidence, though limited, suggests semiterrestrial locomotion, which contrasts with most extant African and Asian colobines that exhibit morphological and physiological adaptations for arboreality and folivory. These differences raise questions regarding the dietary specialization of early colobine taxa and how/if that influenced their dispersion out of Africa and into Eurasia. To further our understanding of the ecology of Plio-Pleistocene cercopithecids, we characterized the dental capabilities and potential dietary adaptations of Dolichopithecus ruscinensis through dental topographic and enamel thickness analyses on an M1 from the locality of Serrat d'en Vacquer, Perpignan (France). We also assessed the feeding behavior of D. ruscinensis through dental microwear texture analysis on a broad sample of fossil molars from fossil sites in France, Greece, Bulgaria, and Romania. Dental topographic and enamel thickness analyses suggest that D. ruscinensis could efficiently process a wide range of foods. Results of the dental microwear texture analysis suggest that its diet ranged from folivory to the consumption of more mechanically challenging foods. Collectively, this suggests a more opportunistic feeding behavior for Dolichopithecus than characteristic of most extant colobines.

Dietary ecology of Alaskan polar bears (Ursus maritimus) through time and in response to Arctic climate change.

Arctic climate change poses serious threats to polar bears (Ursus maritimus) as reduced sea ice makes seal prey inaccessible and marine ecosystems undergo bottom-up reorganization. Polar bears' elongated skulls and reduced molar dentition, as compared to their sister species the grizzly bear (Ursus arctos), are adaptations associated with hunting seals on sea ice and a soft, lipid-rich diet of blubber and meat. With significant declines in sea ice, it is unclear if and how polar bears may be altering their diets. Clarifying polar bear dietary responses to changing climates, both today and in the past, is critical to proper conservation and management of this apex predator. This is particularly important when a dietary strategy may be maladaptive. Here, we test the hypothesis that hard-food consumption (i.e., less preferred foods including bone), inferred from dental microwear texture analysis, increased with Arctic warming. We find that polar bears demonstrate a conserved absence of hard-object feeding in Alaska through time (including approximately 1000 years ago), until the 21st century, consistent with a highly conserved and specialized diet of soft blubber and flesh. Notably, our results also suggest that some 21st-century polar bears may be consuming harder foods (e.g., increased carcass utilization, terrestrial foods including garbage), despite having skulls and metabolisms poorly suited for such a diet. Prior to the 21st century, only polar bears with larger mandibles demonstrated increased hard-object feeding, though to a much lower degree than closely related grizzly bears which regularly consume mechanically challenging foods. Polar bears, being morphologically specialized, have biomechanical constraints which may limit their ability to consume mechanically challenging diets, with dietary shifts occurring only under the most extreme scenarios. Collectively, the highly specialized diets and cranial morphology of polar bears may severely limit their ability to adapt to a warming Arctic.

Technical note: Artificial Resynthesis Technology for the experimental formation of dental microwear textures.

Dental microwear formation on the posterior dentition is largely attributed to an organism's diet. However, some have suggested that dietary and environmental abrasives contribute more to the formation process than food, calling into question the applicability of dental microwear to the reconstruction of diet in the fossil record. Creating microwear under controlled conditions would benefit this debate, but requires accurately replicating the oral environment. This study tests the applicability of Artificial Resynthesis Technology (ART 5) to create microwear textures while mitigating the challenges of past research. ART 5 is a simulator that replicates the chewing cycle, responds to changes in food texture, and simulates the actions of the oral cavity. Surgically extracted, occluding pairs of third molars (n = 2 pairs) were used in two chewing experiments: one with dried beef and another with sand added to the dried beef. High-resolution molds were taken at 0, 50, 100, 2500, and 5000 simulated chewing cycles, which equates to approximately 1 week of chewing. Preliminary results show that ART 5 produces microwear textures. Meat alone may produce enamel prism rod exposure at 5000 cycles, although attrition cannot be ruled out. Meat with sand accelerates the wear formation process, with enamel prism rods quickly obliterated and "pit-and-scratch" microwear forming at approximately 2500 cycles. Future work with ART 5 will incorporate a more thorough experimental protocol with improved controls, pH of the simulated oral environment, and grit measurements; however, these results indicate the potential of ART 5 in untangling the complex variables of dental microwear formation.

Applying dental microwear texture analysis to the living: Challenges and prospects.

OBJECTIVES: The food that people and animals consume leaves microscopic traces on teeth in predictable ways, and analyses of these markings-known as dental microwear analyses-allow us to reverse engineer the characteristics of diet. However, the microwear features of modern human diets are most often interpreted through the lens of ethnographic records. Given the subtle variation within human diets when compared to other species, we need better models of how foods and processing techniques produce marks on teeth. Here, we report on the second study to target the occlusal surface microwear of living human populations, and the first to target populations other than foragers. METHODS: We collected 150 dental impressions from five Kenyan communities: El Molo, Turkana (Kerio), Luhya (Webuye), Luhya (Port Victoria), and Luo (Port Victoria), representing a range of subsistence strategies and associated staple diets-fishing, pastoralism, and agriculture. Our results suggest that the occlusal microwear of these groups records differences in diet. However, biofilm obscured most of the molds obtained despite the steps taken to remove it, resulting in only 38 usable surfaces. RESULTS: Due to the biofilm problem and final sample size, the analysis did not have enough power to demonstrate the differences observed statistically. The results and problems encountered are here explained. CONCLUSIONS: Considering that in vivo studies of dental microwear texture analysis have the potential to increase our understanding of the association between patterns of dental microwear and complex, mixed human diets, resolution of the current pitfalls of the technique is critical.

Multiproxy evidence for leaf-browsing and closed habitats in extinct proboscideans (Mammalia, Proboscidea) from Central Chile.

Proboscideans are so-called ecosystem engineers and are considered key players in hypotheses about Late Pleistocene megafaunal extinctions. However, knowledge about the autoecology and chronology of the proboscideans in South America is still open to debate and raises controversial views. Here, we used a range of multiproxy approaches and new radiocarbon datings to study the autoecology of Chilean gomphotheres, the only group of proboscideans to reach South America during the Great American Biotic Interchange (∼3.1 to 2.7 million years before present). As part of this study, we analyzed stable isotopes, dental microwear, and dental calculus microfossils on gomphothere molars from 30 Late Pleistocene sites (31° to 42°S). These proxies provided different scales of temporal resolution, which were then combined to assess the dietary and habitat patterns of these proboscideans. The multiproxy study suggests that most foraging took place in relatively closed environments. In Central Chile, there is a positive correlation between lower δ13C values and an increasing consumption of arboreal/scrub elements. Analyses of dental microwear and calculus microfossils have verified these leaf-browsing feeding habits. From a comparative perspective, the dietary pattern of South American gomphotheres appears to be constrained more by resource availability than by the potential dietary range of the individual taxa. This multiproxy study is aimed at increasing knowledge of the life history of gomphotheres and thus follows an issue considered one of the greatest challenges for paleontology in South America, recently pointed out by the need to thoroughly understand the role of ecological engineers before making predictions about the consequences of ecosystem defaunation.

Dental microwear texture reflects dietary tendencies in extant Lepidosauria despite their limited use of oral food processing.

Lepidosauria show a large diversity in dietary adaptations, both among extant and extinct tetrapods. Unlike mammals, Lepidosauria do not engage in sophisticated mastication of their food and most species have continuous tooth replacement, further reducing the wear of individual teeth. However, dietary tendency estimation of extinct lepidosaurs usually rely on tooth shape and body size, which allows only for broad distinction between faunivores and herbivores. Microscopic wear features on teeth have long been successfully applied to reconstruct the diet of mammals and allow for subtle discrimination of feeding strategies and food abrasiveness. Here, we present, to our knowledge, the first detailed analysis of dental microwear texture on extant lepidosaurs using a combination of 46 surface texture parameters to establish a framework for dietary tendency estimation of fossil reptilian taxa. We measured dental surface textures of 77 specimens, belonging to herbivorous, algaevorous, frugivorous, carnivorous, ovivorous, insectivorous, molluscivorous, as well as omnivorous species. Carnivores show low density and shallow depth of furrows, whereas frugivores are characterized by the highest density of furrows. Molluscivores show the deepest wear features and highest roughness, herbivores have lower surface roughness and shallower furrows compared to insectivores and omnivores, which overlap in all parameters. Our study shows that despite short food-tooth interaction, dental surface texture parameters enable discrimination of several feeding strategies in lepidosaurs. This result opens new research avenues to assess diet in a broad variety of extant and extinct non-mammalian taxa including dinosaurs and early synapsids.

New model to explain tooth wear with implications for microwear formation and diet reconstruction.

Paleoanthropologists and vertebrate paleontologists have for decades debated the etiology of tooth wear and its implications for understanding the diets of human ancestors and other extinct mammals. The debate has recently taken a twist, calling into question the efficacy of dental microwear to reveal diet. Some argue that endogenous abrasives in plants (opal phytoliths) are too soft to abrade enamel, and that tooth wear is caused principally by exogenous quartz grit on food. If so, variation in microwear among fossil species may relate more to habitat than diet. This has important implications for paleobiologists because microwear is a common proxy for diets of fossil species. Here we reexamine the notion that particles softer than enamel (e.g., silica phytoliths) do not wear teeth. We scored human enamel using a microfabrication instrument fitted with soft particles (aluminum and brass spheres) and an atomic force microscope (AFM) fitted with silica particles under fixed normal loads, sliding speeds, and spans. Resulting damage was measured by AFM, and morphology and composition of debris were determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Enamel chips removed from the surface demonstrate that softer particles produce wear under conditions mimicking chewing. Previous models posited that such particles rub enamel and create ridges alongside indentations without tissue removal. We propose that although these models hold for deformable metal surfaces, enamel works differently. Hydroxyapatite crystallites are "glued" together by proteins, and tissue removal requires only that contact pressure be sufficient to break the bonds holding enamel together.

Untangling the environmental from the dietary: dust does not matter.

Both dust and silica phytoliths have been shown to contribute to reducing tooth volume during chewing. However, the way and the extent to which they individually contribute to tooth wear in natural conditions is unknown. There is still debate as to whether dental microwear represents a dietary or an environmental signal, with far-reaching implications on evolutionary mechanisms that promote dental phenotypes, such as molar hypsodonty in ruminants, molar lengthening in suids or enamel thickening in human ancestors. By combining controlled-food trials simulating natural conditions and dental microwear textural analysis on sheep, we show that the presence of dust on food items does not overwhelm the dietary signal. Our dataset explores variations in dental microwear textures between ewes fed on dust-free and dust-laden grass or browse fodders. Browsing diets with a dust supplement simulating Harmattan windswept environments contain more silica than dust-free grazing diets. Yet browsers given a dust supplement differ from dust-free grazers. Regardless of the presence or the absence of dust, sheep with different diets yield significantly different dental microwear textures. Dust appears a less significant determinant of dental microwear signatures than the intrinsic properties of ingested foods, implying that diet plays a critical role in driving the natural selection of dental innovations.

Dietary ecology of fossil Theropithecus: Inferences from dental microwear textures of extant geladas from ecologically diverse sites.

As the only extant graminivorous primate, gelada monkeys (Theropithecus gelada) offer unique insights into how hominins and other extinct primates with strong C4 isotopic signatures may have subsisted on graminoid-rich diets. Fossil Theropithecus species sharing a strong C4 signal (i.e., Theropithecus brumpti, Theropithecus darti, and Theropithecus oswaldi) have been reconstructed as predominantly graminivorous and potentially in ecological competition with contemporaneous hominins. However, inferring the breadth and variation of diet in these species (and therefore hominins) has proven problematic. Understanding how ecological variation within extant geladas impacts microwear and isotopic signatures may contribute to reconstructions of diet in fossil Theropithecus. Here, we build on a recent study at an ecologically intact tall grass ecosystem (Guassa, Ethiopia) that expanded the known diversity of gelada diets by demonstrating lower reliance on graminoids, greater consumption of forbs, and greater dietary species richness than previously described at disturbed sites. We used dental microwear texture analysis to explore how dietary variation among extant geladas may inform our understanding of the diets of fossil Theropithecus. First, we compared the dental microwear textures of geladas at Guassa to those of geladas from other sites. The microwear textures of geladas at Guassa exhibited more complexity, less anisotropy, and more variance in anisotropy and heterogeneity, reflecting the greater dietary diversity of Guassa geladas. Comparing microwear texture variables among this expanded gelada sample to those for T. brumpti, T. oswaldi, and T. darti yielded no significant differences. These results raise the intriguing possibility that data on how ecological variation and diet impact dental microwear and (possibly) isotopic signatures in extant geladas can be used to reconstruct the diets of extinct theropiths and, more broadly, hominins with strong C4 isotopic signatures. We conclude that extant gelada populations offer a powerful analog for inferring dietary variation among predominantly graminivorous fossil primates.

Silicon-based plant defences, tooth wear and voles.

Plant-herbivore interactions are hypothesized to drive vole population cycles through the grazing-induced production of phytoliths in leaves. Phytoliths act as mechanical defences because they deter herbivory and lower growth rates in mammals. However, how phytoliths impair herbivore performance is still unknown. Here, we tested whether the amount of phytoliths changes tooth wear patterns. If confirmed, abrasion from phytoliths could play a role in population crashes. We applied dental microwear texture analysis (DMTA) to laboratory and wild voles. Lab voles were fed two pelleted diets with differing amounts of silicon, which produced similar dental textures. This was most probably due to the loss of food mechanical properties through pelletization and/or the small difference in silicon concentration between diets. Wild voles were trapped in Poland during spring and summer, and every year across a population cycle. In spring, voles feed on silica-rich monocotyledons, while in the summer they also include silica-depleted dicotyledons. This was reflected in the results; the amount of silica therefore leaves a traceable record in the dental microwear texture of voles. Furthermore, voles from different phases of population cycles have different microwear textures. We tentatively propose that these differences result from grazing-induced phytolith concentrations. We hypothesize that the high amount of phytoliths in response to intense grazing in peak years may result in malocclusion and other dental abnormalities, which would explain how these silicon-based plant defences help provoke population crashes. DMTA could then be used to reconstruct vole population dynamics using teeth from pellets or palaeontological material.

Eating through time: Understanding dietary practices across late prehistory in the northeastern Iberian Peninsula.

OBJECTIVE: This study seeks to contribute to the current understanding of dietary variation in the late Prehistory of the northeastern Iberian Peninsula by examining buccal dental microwear patterns alongside archeological data from the same populations. MATERIALS AND METHODS: Teeth from 84 adult individuals from eight distinct samples spanning the Middle-Late Neolithic to the Middle Bronze Age (Cova de l'Avi, Cova de Can Sadurní, Cova de la Guineu, Cova Foradada, Cova del Trader, Roc de les Orenetes, Cova del Gegant, Cova dels Galls Carboners) were analyzed using optical microscopy to examine buccal dental microwear patterns. RESULTS: The analysis did not reveal clear chronological contrasts in the dietary habits of these samples. Nevertheless, significant differences emerged among the samples, leading to their classification into two distinct sets based on the abrasiveness of the diet informed by the microwear patterns. These findings offer similarities and differences among samples in the Iberian Peninsula, shedding light on the diverse lifestyles of these individuals. DISCUSSION: Integrating our new results with other available proxies points to a multifaceted specialization in dietary patterns among these samples, influenced by factors such as habitat, resource selection, and available technology. By contextualizing the results within the broader context of the Iberian Peninsula, this research discerns shared characteristics and distinctive adaptations in the dietary practices and subsistence strategies of these groups. Ultimately, this study contributes to a deeper understanding of the intricate interplay between culture and environment in shaping human diets throughout late Prehistory.

Nutritional reconstruction in an early modern population: Searching for a relationship between dental microwear and bone element composition.

BACKGROUND: Observing the microwear patterns of the dental crowns enamel surface can provide information on the ingredients and structure of the food consumed, but also on eating habits and lifestyle. Major role in reconstructing the diet and lifestyle of past populations is played by the analysis of alkaline earth metals, such as strontium, barium, zinc and calcium. Ba and Sr are indicators of the consumption of vegetables, plants (cereals and legumes) and marine organisms. This study aims to assess dietary diversity and identify its components based on microscopic techniques and chemical analyses of material from early modern archaeological sites in Wroclaw, Poland. METHODS: The material consisted of 36 permanent molars and the intrasternal parts of 122 first ribs, collected from 6 Wroclaw early modern cemeteries. Tooth microwear was evaluated on Scanning electron microscopy images, with Microwear 4.02 software. Bone chemical composition (Ca, P, Ba, Sr content) was evaluated with mass spectrometry. RESULTS: Most lines were present on the teeth from St. Mary Magdalene Cemetery, with the lowest average number of lines observed on the teeth from St. Barbara Cemetery. The Ca/P ratios calculated for different sites formed two clusters that allows to distinguish two groups of archaeological sites with different bone preservation status. Number of differences in Ba/Sr, Sr/Ca, Ba/Ca ratios was found between disctinct archaeological sites. A number of correlations were found between the concentration of the chemical elements, but no statistically significant correlation was found between the microwear characteristics and the proportion of the elements studied. Some strong correlations were found between microwear features and the Ca/P ratio. CONCLUSIONS: the different values of Sr/Ca, Ba/Ca and Ba/Sr ratios indicate different diets in the different communities. The data obtained indicate a mixed diet, with a relatively high proportion of animal products throughout Wroclaw. Conclusions should be treated with caution due to secondary diagenesis. The lack of interdependence between microwear and chemical composition characteristics suggests that the two methods should be considered complementary and not overlapping, as they provide different insights into the diets of past populations. The comparison of microwear between different sites should always take into account secondary diagenesis and the burial environment, as these influence the characteristics of microwear.

Experimental approaches to assess the effect of composition of abrasives in the cause of dental microwear.

Dental microwear is used to investigate feeding ecology. Animals ingest geological material in addition to food. The full effect of geological abrasives on tooth wear is unknown. To evaluate mineralogical abrasives as tooth wear agents, rats were fed food manufactured with quartz silt, diatomaceous earth, and calcium carbonate. Rats were assigned to treatments and fed for 15 days. Molars were scanned with a Sensofar Plu Neox confocal microscope and evaluated using ISO-25178-2 parameters and traditional microwear variables using light microscopy. Using a pellet-diet as the control, all treatments had influence on microwear and discriminant function analyses indicated that unique surface textures had been produced. ISO variables with high discriminatory values were correlated to scratch and pit frequencies, but more ISO parameters identified changes associated with numbers of scratches than changes associated with pits. The microwear changes associated with the abrasive inclusions were co-dependent on the type of diet that the abrasives had been added to. The abrasives had less effect with pellets but produced more modified and more differentiated microwear when added to the transgenic dough. Although abrasives produce distinctive surface textures, some knowledge of the properties of food with the abrasives is needed to identify the abrasive agent.

Post-mortem enamel surface texture alteration during taphonomic processes-do experimental approaches reflect natural phenomena?

Experimental approaches are often used to better understand the mechanisms behind and consequences of post-mortem alteration on proxies for diet reconstruction. Dental microwear texture analysis (DMTA) is such a dietary proxy, using dental wear features in extant and extinct taxa to reconstruct feeding behaviour and mechanical food properties. In fossil specimens especially, DMTA can be biased by post-mortem alteration caused by mechanical or chemical alteration of the enamel surface. Here we performed three different dental surface alteration experiments to assess the effect of common taphonomic processes by simplifying them: (1) tumbling in sediment suspension to simulate fluvial transport, (2) sandblasting to simulate mechanical erosion due to aeolian sediment transport, (3) acid etching to simulate chemical dissolution by stomach acid. For tumbling (1) we found alteration to be mainly dependent on sediment grain size fraction and that on specimens tumbled with sand fractions mainly post-mortem scratches formed on the dental surface, while specimens tumbled with a fine-gravel fraction showed post-mortem formed dales. Sandblasting (2) with loess caused only negligible alteration, however blasting with fine sand quartz particles resulted in significant destruction of enamel surfaces and formation of large post-mortem dales. Acid etching (3) using diluted hydrochloric acid solutions in concentrations similar to that of predator stomachs led to a complete etching of the whole dental surface, which did not resemble those of teeth recovered from owl pellets. The experiments resulted in post-mortem alteration comparable, but not identical to naturally occurring post-mortem alteration features. Nevertheless, this study serves as a first assessment and step towards further, more refined taphonomic experiments evaluating post-mortem alteration of dental microwear texture (DMT).

From leaves to seeds? The dietary shift in late Miocene colobine monkeys of southeastern Europe.

Extant colobine monkeys are specialized leaf eaters. But during the late Miocene, western Eurasia was home to colobines that were less efficient at chewing leaves than they were at breaking seed shells. To understand the link between folivory and granivory in this lineage, the dietary niche of Mesopithecus delsoni and Mesopithecus pentelicus was investigated in southeastern Europe, where a major environmental change occurred during the late Miocene. We combined dental topographic estimates of chewing efficiency with dental microwear texture analysis of enamel wear facets. Mesopithecus delsoni was more efficient at chewing leaves than M. pentelicus, the dental topography of which matches an opportunistic seed eater. Concurrently, microwear complexity increases in M. pentelicus, especially in the northernmost localities corresponding to present-day Bulgaria. This is interpreted as a dietary shift toward hard foods such as seeds or tubers, which is consistent with the savanna and open mixed forest biomes that covered Bulgaria during the Tortonian. The fact that M. delsoni was better adapted to folivory and consumed a lower amount of hard foods than M. pentelicus suggests that colobines either adapted to folivory before their dispersal to Europe or evolved adaptations to leaf consumption in multiple occurrences.

Dietary ecology of the scimitar-toothed cat Homotherium serum.

The scimitar-toothed cat Homotherium was one of the most cosmopolitan cats of the Pleistocene, present throughout Eurasia, Africa, and the Americas until at least ~28 thousand years ago.1-3 Friesenhahn Cave (Bexar County, Texas) contains some of the best-preserved specimens of Homotherium serum alongside an abundance of juvenile mammoths, leading some to argue that H. serum preferentially hunted juvenile mammoths.1,4 Dietary data of Homotherium are rare, with their ecology inferred from morphological, taphonomic, and genetic data.1,3-10 Here, we use a multi-proxy approach to clarify the dietary ecology of H. serum as compared to extinct and extant cats and their relatives. Dental microwear texture analysis (DMTA) reveals that H. serum consumed soft and tough foods, similar to the extant cheetah, which actively avoids bone,11,12 but in stark contrast to extant lions and hyenas, which are observed to engage in durophagy (i.e., bone processing).11-14 DMTA data are consistent with taphonomic evidence of bone defleshing and the absence of bone-crunching behavior in H. serum. Stable carbon isotope values of H. serum indicate a clear preference for C4 grazers including juvenile mammoths, in agreement with taphonomic evidence suggestive of a "Homotherium den"1,4 and morphological data indicative of a relatively cursorial lifestyle.6-8 Notably, the inferred diet of H. serum contrasts with the extinct dirk-tooth sabertooth cat Smilodon fatalis, which preferred forest/woodland prey and engaged in bone processing.15-19Homotherium serum exhibited a novel combination of morphological adaptations for acquiring open-country prey, consuming their soft and tough flesh-including the tough flesh of juvenile mammoths. VIDEO ABSTRACT.