Dental Microwear Texture Research Articles

Dietary variability of extinct tayassuids and modern white-lipped peccaries (Tayassu pecari) as inferred from dental microwear and stable isotope analysis

Prior geochemical work documents dietary shifts coincident with climate change in extinct peccaries, with taxa typically shifting between browsing and mixed-feeding. This study employs dental microwear texture analysis (DMTA) and stable carbon isotopes to interpret the diet of extinct peccaries in Florida, specifically Platygonus, Mylohyus, and Protherohyus from the late Miocene throughout the Pleistocene, to evaluate how dietary behavior has fluctuated over time. When Mylohyus and Protherohyus coexisted in the Hemphillian, Mylohyus consumed C3 food sources with harder textures, consistent with the consumption of woody browse, while Protherohyus consumed a greater proportion of C4 vegetation (likely grass). During the Blancan, both Platygonus and Mylohyus can be considered primarily C3 browsers, based on both DMTA and stable isotope data. However, during the Irvingtonian, both Mylohyus and Platygonus consumed a larger proportion of C4 vegetation than during previous North American Land Mammal Ages (NALMAs). Platygonus consumed predominantly C3 vegetation during the Rancholabrean, while Mylohyus consumed a mixture of C3 and C4 vegetation in more open environments. Independent of NALMA, Platygonus consumed predominantly tough vegetation, (e.g., tough leaves and/or grass) while Mylohyus consumed harder food items, consistent with morphological differences in their teeth. In contrast, extant Tayassu peccaries are obligate C3 feeders and show no evidence of C4 consumption. Further, Tayassu are indistinguishable in all dental microwear textural properties from both of their extinct relatives, suggesting that while extant peccaries eat primarily foods from forested environments, those foods are highly variable in textural properties. Collectively, these data suggest that extinct peccaries, Mylohyus and Platygonus, altered their diet over time and possibly in response to changing climates.

Brief communication: Dental microwear and diet of Homo naledi.

A recent study of dental chipping suggested that Homo naledi teeth were exposed to "acute trauma" on a regular basis during life, presumably from the consumption of grit-laden foods. This follows debate concerning the etiology of dental chips in South African hominin teeth that dates back more than half a century. Some have argued that antemortem chips result from consumption of hard foods, such as nuts and seeds or bone, whereas others have claimed that exogenous grit on roots and tubers are responsible. Here we examine the dental microwear textures of H. naledi, both to reconstruct aspects of diet of these hominins and to assess the possibility that hard foods (gritty or otherwise) are the culprits for the unusually high antemortem chip incidence reported. We made high-resolution replicas of original molars and found that ten individuals preserve antemortem wear. These were scanned by white-light scanning confocal profilometry and analyzed using scale-sensitive fractal analysis. Resulting data were compared with those published for other fossil hominins and extant non-human primates. Our results indicate that H. naledi had complex microwear textures dominated by large, deep pits. The only known fossil hominin with higher average texture complexity is Paranthropus robustus, and the closest extant primates in a comparative baseline series appear to be the hard-object feeder, Cercocebus atys, and the eurytopic generalist, Papio ursinus. This study suggests that H. naledi likely consumed hard and abrasive foods, such as nuts or tubers, at least on occasion, and that these might well be responsible for the pattern of chipping observed on their teeth.

Feeding ecology of Tragelaphini (Bovidae) from the Shungura Formation, Omo Valley, Ethiopia: Contribution of dental wear analyses

To better understand the environmental conditions that prevailed in the Plio-Pleistocene Shungura Formation, Lower Omo Valley, Ethiopia, we analyze the feeding preferences of Tragelaphini, the third most common tribe of Shungura bovids. Molar mesowear and dental microwear texture analyses were applied to three species (Tragelaphus rastafari, T. nakuae, and T. gaudryi) and body mass estimates were calculated for the T. rastafari-nakuae lineage to test whether dietary shifts were linked to body mass changes. We compare our results with previous work on stable carbon isotopes (δ13C) of enamel, which indicated that tragelaphins from the Shungura Formation possessed dietary flexibility. We found that the both the T. rastafari-nakuae lineage and T. gaudryi maintained a mixed feeding dietary niche, with varying proportions of C3 versus C4 inputs, from ~3.6 to >2 Ma. Our results show that T. rastafari consumed more browse than its descendant, T. nakuae, which was a mixed feeder consuming a greater proportion of C4 dicots ~ 2.8 Ma. The T. rastafari-T. nakuae dietary shift may reflect environmental changes in the Shungura Formation during this time, but appears to be offset from body mass increases in this lineage, which occurred gradually through the Plio-Pleistocene. This study highlights the importance of a multi-proxy approach to precisely determine the dietary ecologies of extinct bovids and points to how each proxy offers a slightly different perspective on the ecology of fossil organisms.

Enamel surface topography analysis for diet discrimination. A methodology to enhance and select discriminative parameters

Tooth wear and, more specifically, dental microwear texture is a dietary proxy that has been used for years in vertebrate paleoecology and ecology. DMTA, dental microwear texture analysis, relies on a few parameters related to the surface complexity, anisotropy and heterogeneity of the enamel facets at the micrometric scale. Working with few but physically meaningful parameters helps in comparing published results and in defining levels for classification purposes. Other dental microwear approaches are based on ISO parameters and coupled with statistical tests to find the more relevant ones.The present study roughly utilizes most of the aforementioned parameters in their more or less modified form. But more than parameters, we here propose a new approach: instead of a single parameter characterizing the whole surface, we sample the surface and thus generate 9 derived parameters in order to broaden the parameter set.The identification of the most discriminative parameters is performed with an automated procedure which is an extended and refined version of the workflows encountered in some studies. The procedure in its initial form includes the most common tools, like the ANOVA and the correlation analysis, along with the required mathematical tests. The discrimination results show that a simplified form of the procedure is able to more efficiently identify the desired number of discriminative parameters. Also highlighted are some trends like the relevance of working with both height and spatial parameters, as well as the potential benefits of dimensionless surfaces. On a set of 45 surfaces issued from 45 specimens of three modern ruminants with differences in feeding preferences (grazing, leaf-browsing and fruit-eating), it is clearly shown that the level of wear discrimination is improved with the new methodology compared to the other ones.

Deer in an arid habitat: dental microwear textures track feeding adaptability

Teeth constitute a bridge between an organism and its environment. Dental wear is a good proxy for (paleo) ecologists to better comprehend the ecology and habitat of modern and extinct species. In this study, we showed Dental Microwear Texture Analysis to be a useful tool, integrating not only specific plant selection but also dietary quality and digestibility in order to understand resource use. Resource-partitioning, seasonal and sexual variations in the diet of two deer species on a Spanish game estate are explored here through Dental Microwear Texture Analysis. This Mediterranean area is on the fringes of the average European environments in terms of constraints and diet for extant red and fallow deer, resulting in an opportunity to understand their ability to live in harsh conditions and the feeding strategies they developed. These two taxa already experienced harsh living conditions during the Pleistocene. Dental microwear texture shows both deer feeding differently on the herbaceous layer in a context where it is the main resource consumed annually. These differences are linked to body mass. With its smaller incisor arcade, Dama dama is able to be more selective, hence focusing on less fibrous parts of forages. Cervus elaphus is more plastic, with dietary variations corresponding to seasonal plant availability and the physiological requirements of stags and does. In general, C. elaphus consumes a more fibrous and less digestible vegetable material than D. dama . This study brings light on the feeding behavior of the two game species under constraint conditions. The results of this study are discussed in terms of realized vs potential ecological niche.

Dental microwear and controlled food testing on sheep: The TRIDENT project

Abstract Here, we present a short review of the most recent results that have come out of the TRIDENT project. This project aims to model tooth wear by performing controlled food testing on sheep. This approach offers us the opportunity to test various scientific questions which colleagues, working exclusively on fossil and modern wild species, have been unable to answer. Whereas several experimental studies were done at the scale of food particles, TRIDENT explores these questions at the scale of the living organism chewing thousands of bio-silica phytoliths all embedded in cell-walls, a structural condition that undoubtedly influences the way wear is generated. Our first results concern the effects of different food types, first free of dust and then with dust, thus reproducing natural conditions. After exploring the effects of seeds of different size and hardness, we have also further investigated the unexpected results highlighted over the course of the experimentation. Among them is the relevance of the practice to enlarge sample size by including different facets of the teeth and how this practice affects our results and interpretation on diet reconstruction. Finally we show some preliminary results of an alternative analytic approach to better discriminate between different dental microwear textures.

Dental topography and microwear texture in Sapajus apella

Abstract Dental microwear texture pattern has been associated with aspects of diet for a broad range of mammalian taxa. The basic idea is that soft, tough foods are sheared with a steeper angle of approach between opposing occlusal surfaces, whereas hard, brittle items are crushed with forces perpendicular to those surfaces; and this difference is manifested in anisotropic, striated microwear textures for tough foods, and complex, pitted ones for hard objects. Other factors may, however, influence microwear texture pattern and confound diet signals. For example, if tooth surface slope influences angle of approach between opposing teeth, then perhaps wear-related changes in tooth shape could affect microwear pattern. This study evaluates the effects of occlusal topography on microwear texture for a series of variably worn upper second molars of one primate species, Sapajus apella. Results indicate no significant covariation between any measured topographic attribute (average slope, angularity, relief) and microwear texture variable (complexity, anisotropy, textural fill volume). This suggests that, for this taxon at least, wear-related changes in tooth form do not affect microwear pattern in a consistent manner. This implies that variably worn teeth can be included in samples for comparisons aimed at distinguishing groups by diet.

Dental microwear texture analysis of extant sika deer with considerations on inter-microscope variability and surface preparation protocols

Abstract Recently, dental microwear texture analysis (DMTA) has been applied to various kinds of vertebrates to infer dietary preference. More data are needed on inter-microscope variability to assure the objectivity and repeatability of this method. In the present paper, we investigated inter-microscope variability between two confocal laser microscopes with different specifications, as well as variability due to different protocols applied to the obtained surface before DMTA. We used two different methods of DMTA: the scale sensitive fractal analysis (SSFA) and the surface texture analysis (STA). We collected DMTA data of extant Japanese sika deer populations with varying diets. We found that different protocols produced significantly different results for both SSFA and STA, whereas nearly two thirds of the parameters were not significantly different between the machines when applying the same pre-analysis protocol. Finally, we analyzed DMTA data of 244 sika deer from 11 populations. Twenty nine parameters were significantly different among the populations. Tooth enamel surface of grazing sika deer is dominated by a number of well-aligned scratches, whereas that of browsing deer is more flattened and characterized by more sporadic pits. Therefore, DMTA can identify intraspecific variation in diets, which is smaller than the interspecific dietary variation in extant ruminants.

Dietary ecology of Pleistocene mammoths and mastodons as inferred from dental microwear textures

The Columbian mammoth (Mammuthus columbi) and the American mastodon (Mammut americanum) have traditionally been considered to have been ecologically distinct, with mammoths often characterized as cosmopolitan grazers or mixed feeders and mastodons as forest-dwelling browsers. However, these large-bodied proboscideans occupying temperate, often resource-limiting environments in Pleistocene North American would have necessitated a much wider range of resources. For the isolated pygmy mammoth (Mammuthus exilis) of California's Channel Islands, the resource-limited nature of its insular home may have exacerbated the need for consumption of a wide range of less-preferred resources. The goal of this study is to better understand the degree to which each of these taxa consumed tough and/or hard food items, including grass, leaves, and woody browse in their respective environments. To this end, we examined the dental microwear of Pleistocene mammoths and mastodons to address the following questions: 1) do mammoths and mastodons with known differences in diet (via carbon isotopes) have similar dental microwear attributes?, 2) do juvenile and adult mammoth and mastodons consume foods with similar textural properties?, and 3) did the Channel Islands mammoths consume food with similar textural properties as the mainland Columbian mammoths? Our results demonstrate that the mammoths and mastodons here examined ate foods with similar textural properties, despite consuming plants with disparate stable isotope values. These data suggest that mammoths and mastodons were generalists (in regards to dietary textures) and did not eat softer or tougher foods as juveniles. Further, the Channel Islands mammoths ate food items with more variable textural properties (including a greater incidence of hard foods) than Columbian mammoths from Texas. While more work is needed to assess the ubiquity of these results across time and space, collectively, these data suggest that extinct proboscideans are generalist feeders similar to extant elephants.

Feeding ecology of Eucladoceros ctenoides as a proxy to track regional environmental variations in Europe during the early Pleistocene

The early Pleistocene is represented by a succession of glacial–interglacial cycles characterized by a general tendency towards global cooling, with increasing aridity and seasonality. The large deer Eucladoceros is found in abundance in Europe during this period of faunal dispersions. The dietary plasticity of Eucladoceros and how it can mirror early Pleistocene climatic variations will be explored here using Dental Microwear Texture Analysis. The wide range of dental microwear textures for Eucladoceros reflects a low selectivity and high plasticity in its diet. It is an appropriate proxy to track vegetal resource availability. Oscillations were identified between a browsing and a grazing signal. This study proposes that a browsing signal is associated with a fossil assemblage deposited during an interglacial event characterized by warmer temperatures and deciduous vegetation. A grazing signal more likely indicates a glacial event with cooler temperatures and a developed herbaceous, bushy layer.

A molar microwear texture analysis of pitheciid primates.

Dental microwear textures have been examined for a broad range of extant primates to assess their efficacy for reconstructing diets of fossil species. To date though, no dental microwear texture data have been published for pitheciid molars, despite reported variation in degree of sclerocarpy and, by extension, the fracture properties of foods these platyrrhines eat. While all pitheciids eat hard or tough seeds, Chiropotes and Pithecia have been documented to consume more than Callicebus. In this study, we explored whether measures of molar microwear texture complexity discriminate taxa following variation in reliance upon seeds, and whether dispersion among variables is greatest in Callicebus, which has the most variable diet. Here we report results for a study of microwear textures on M2 "Phase II" facets of Ch. satanas (N = 14), P. irrorata (N = 8), and Ca. moloch (N = 24) from the Brazilian Amazon (Oriximina, UHE Samuel, and Taperinha, respectively). Textures examined using a scanning confocal profiler showed significant differences in central tendencies for three measures: mean dale area (Sda), anisotropy (Str), and heterogeneity (HAsfc9 ). Ten measures showed significant differences in dispersion, with Callicebus being significantly more variable in eight of those ten. These results demonstrate that the pitheciids with different morphological adaptations and dietary reliance on seeds differ in their dental microwear textures, though less than initially hypothesized. Measures of dispersion, especially, show potential for identifying dietary variability.

Regional variation in the browsing diet of Pleistocene Mammut americanum (Mammalia, Proboscidea) as recorded by dental microwear textures

Analyses into the feeding ecology of Mammut americanum have reconstructed this extinct proboscidean as a forest-dwelling browser that thrived across North America during the Pleistocene. However, the level of variability in mastodon diet that may have existed across its spatio-temporal range remains unresolved. We address this deficiency through comparison of dental microwear textures in a large sample (N=65) of M. americanum teeth from six geographic and chronologically distinct locations from the Late Pleistocene of North America. Mastodon microwear textures correspond to a woody browsing diet, congruent with results from other dietary proxies. However, microwear textures reveal that southern populations from Florida (associated with a cypress swamp habitat) had a slightly softer, tougher browsing diet compared to northern populations (associated with boreal forest and open-pine parkland habitats) in the Late Pleistocene. In addition, there was no significant difference in microwear variables associated with food hardness or toughness in mastodons from two temporally distinct populations from Missouri, despite a significant environmental shift from open-pine parkland to boreal forest through time. Our findings elucidate M. americanum as a species with some plasticity in its browsing strategy across its range, with regional populations capable of having different diets yet able to maintain their ecological niche in the face of local environmental shifts in the Late Pleistocene. This has implications for the future testing of environmentally-induced extinction hypotheses during the latest Pleistocene and also illustrates the importance of measuring population-level dietary variation to better understand total feeding ecology in an extinct species.

Palaeoecology of cave bears as evidenced by dental wear analysis: a review of methods and recent findings

The study of dental wear was first used years ago to infer the palaeoecology of fossil mammals and in particular their diet. Results depend predominantly on the scale of the analysis used. Analyses of dental macrowear, mesowear or microwear do not provide the same type of dietary information, be it about the seasonal, annual or lifetime diet. This contribution focuses on emblematic species, cave bears (Ursidae), in particular Ursus spelaeus spelaeus. Methods used by previous researchers to infer their dietary preferences and thus their palaeoecology are reviewed and compared. This review is complemented by an analysis of several specimens of cave bears from the Goyet cave in Belgium, using dental microwear texture analysis (DMTA), a methodology widely applied for reconstructing palaeodiets. Three main conclusions are drawn here: (1) DMTA is the method that provides the most precise palaeobiological inferences; (2) during the pre-dormancy period, cave bears show dietary flexibility; (3) dental wear alone might be not sufficient to provide a complete reconstruction of the cave bear palaeodiet.

Dental microwear and Pliocene paleocommunity ecology of bovids, primates, rodents, and suids at Kanapoi

Reconstructions of habitat at sites like Kanapoi are key to understanding the environmental circumstances in which hominins evolved during the early Pliocene. While Australopithecus anamensis shows evidence of terrestrial bipedality traditionally associated with a more open setting, its enamel has low δ13C values consistent with consumption of C3 foods, which predominate in wooded areas of tropical Africa. Habitat proxies, ranging from paleosols and their carbonates to associated herbivore fauna and their carbon isotope ratios, suggest a heterogeneous setting with both grass and woody plant components, though the proportions of each have been difficult to pin down. Here we bring dental microwear texture analysis of herbivorous fauna to bear on the issue. We present texture data for fossil bovids, primates, rodents, and suids (n = 107 individuals in total) from the hominin bearing deposits at Kanapoi, and interpret these in the light of closely related extant mammals with known differences in diet. The Kanapoi bovid results, for example, are similar to those for extant variable grazers or graze-browse intermediate taxa. The Kanapoi suid data vary by taxon, with one similar to the pattern of extant grazers and the other more closely resembling mixed feeders. The Kanapoi primates and rodents are more difficult to associate with a specific environment, though it seems that grass was likely a component in the diets of both. All taxa evince microwear texture patterns consistent with a mosaic of discrete microhabitats or a heterogeneous setting including both tree and grass components.

Dietary behaviour of man-eating lions as revealed by dental microwear textures

Lions (Panthera leo) feed on diverse prey species, a range that is broadened by their cooperative hunting. Although humans are not typical prey, habitual man-eating by lions is well documented. Fathoming the motivations of the Tsavo and Mfuwe man-eaters (killed in 1898 in Kenya and 1991 in Zambia, respectively) may be elusive, but we can clarify aspects of their behaviour using dental microwear texture analysis. Specifically, we analysed the surface textures of lion teeth to assess whether these notorious man-eating lions scavenged carcasses during their depredations. Compared to wild-caught lions elsewhere in Africa and other large feliforms, including cheetahs and hyenas, dental microwear textures of the man-eaters do not suggest extreme durophagy (e.g. bone processing) shortly before death. Dental injuries to two of the three man-eaters examined may have induced shifts in feeding onto softer foods. Further, prompt carcass reclamation by humans likely limited the man-eaters’ access to bones. Man-eating was likely a viable alternative to hunting and/or scavenging ungulates due to dental disease and/or limited prey availability.

Anterior dental microwear textures show habitat-driven variability in Neandertal behavior

The causes of Neandertal anterior tooth wear patterns, including labial rounding, labial scratches, and differential anterior-posterior wear, have been debated for decades. The most common explanation is the “stuff-and-cut” hypothesis, which describes Neandertals clamping down on a piece of meat and slicing a portion close to their lips. “Stuff-and-cut” has been accepted as a general aspect of Neandertal behavior without fully assessing its variability. This study analyzes anterior dental microwear textures across habitats, locations, and time intervals to discern possible variation in Neandertal anterior tooth-use behavior.Forty-five Neandertals from 24 sites were analyzed, represented by high-resolution replicas of permanent anterior teeth. The labial surface was scanned for antemortem microwear using a white-light confocal profiler. The resultant 3D-point clouds, representing 204 × 276 μm for each specimen, were uploaded into SSFA software packages for texture characterization. Statistical analyses, including MANOVAs, ANOVAs, and pairwise comparisons, were completed on ranked microwear data. Neandertal descriptive statistics were also compared to 10 bioarchaeological samples of known or inferred dietary and behavioral regimes.The Neandertal sample varied significantly by habitat, suggesting this factor was a principal driving force for differences in Neandertal anterior tooth-use behaviors. The Neandertals from open habitats showed significantly lower anisotropy and higher textural fill volume than those inhabiting more closed, forested environments. The texture signature from the open-habitat Neandertals was most similar to that of the Ipiutak and Nunavut, who used their anterior teeth for intense clamping and grasping behaviors related to hide preparation. Those in more closed habitats were most similar to the Arikara, who did not participate in non-dietary behaviors. These Neandertal individuals had a broad range of texture values consistent with non-dietary and dietary behaviors, suggesting they varied more in anterior tooth-use behaviors and exploited a wider variety of plant and animal resources than did those from open habitats.

Buccal dental microwear texture and catarrhine diets.

Two-dimensional dental microwear analyses on occlusal and nonocclusal enamel surfaces have been widely applied to reconstruct the feeding behaviors of extant primates and to infer ecological adaptations in fossil hominins. To date, analyses of dental microwear texture, using three-dimensional, Scale-Sensitive Fractal Analysis approaches has only been applied to occlusal surfaces. Here, for the first time, we apply this 3D proxy to buccal enamel surfaces of catarrhine primates of known feeding ecologies to assess the utility of nonocclusal microwear texture variables as indicators of dietary habits. Buccal microwear texture attributes were collected from high-resolution second molar casts in a sample of seven extant African catarrhine taxa with differing dietary behaviors. A white-light confocal microscope with a 100× objective lens was used to record six microwear texture variables that assess complexity, anisotropy, heterogeneity, and textural fill volume. The physical properties and variation in hardness of ingested foods is reflected by significant differences in the microwear variables on buccal enamel surfaces between species, which is in agreement with early reports using 2D microwear signatures of the same samples. Species that consume hard brittle items showed high buccal enamel complexity and low anisotropy values, while folivorous species that consume tough foods revealed high anisotropy and low complexity enamel patterns. Buccal microwear texture analysis on enamel surfaces clearly reflects diet-related variation in nonhuman primates. Our findings indicate that microwear texture attributes on nonworking enamel surfaces provide an alternative procedure for reconstructing dietary behavior when wear facets on occlusal surfaces are lacking.

Assessing niche conservatism using a multiproxy approach: dietary ecology of extinct and extant spotted hyenas

AbstractA central premise of bioclimatic envelope modeling is the assumption of niche conservatism. Whereas such assumptions are testable in modern populations, it is unclear whether niche conservatism holds over deeper time spans and over very large geographic ranges. Hyaenids occupied a diversity of ecological niches over time and space, and until the end-Pleistocene they occurred in Europe and most of Asia, with Asian populations ofCrocutasuggested as being genetically distinct from their closest living relatives. Further, little is known regarding whether and how the dietary ecology of extinct populations ofCrocutadiffered from those of their extant African counterparts. Here, we use a multiproxy approach to assess an assumption of conserved dietary ecology in late Pleistocene extant spotted hyenas via finite element analysis, dental microwear texture analysis, and a novel dental macrowear method (i.e., whether teeth are minimally, moderately, or extremely worn, as defined by degree of dentin exposure) proposed here. Results from finite element simulations of the masticatory apparatus of Chinese and AfricanCrocutademonstrate lower skull stiffness and higher stress in the orbital region of the former when biting with carnassial teeth, suggesting that ChineseCrocutacould not process prey with the same degree of efficiency as extantCrocuta crocuta. Dental microwear texture data further support this interpretation, as ChineseCrocutahave intermediate and indistinguishable complexity values (indicative of hard-object feeding) between the extant African lion (Panthera leo) and extant hyenas (C. crocuta,Hyaena hyaena, andParahyaena brunnea), being most similar to the omnivorousP. brunnea. The use of dental macrowear to infer dietary behavior may also be possible in extinct taxa, as evinced by dietary correlations between extant African feliforms and dental macrowear assignments. Collectively, this multiproxy analysis suggests that ChineseCrocutamay have exhibited dietary behavior distinct from that of livingC. crocuta, and assumptions of niche conservatism may mask significant dietary variation in species broadly distributed in time and space.

Dietary responses of Sahul (Pleistocene Australia–New Guinea) megafauna to climate and environmental change

AbstractThroughout the late Quaternary, the Sahul (Pleistocene Australia–New Guinea) vertebrate fauna was dominated by a diversity of large mammals, birds, and reptiles, commonly referred to as megafauna. Since ca. 450–400Ka, approximately 88 species disappeared in Sahul, including kangaroos exceeding 200kg in size, wombat-like animals the size of hippopotamuses, flightless birds, and giant monitor lizards that were likely venomous. Ongoing debates over the primary cause of these extinctions have typically favored climate change or human activities. Improving our understanding of the population biology of extinct megafauna as more refined paleoenvironmental data sets become available will assist in identifying their potential vulnerabilities. Here, we apply a multiproxy approach to analyze fossil teeth from deposits dated to the middle and late Pleistocene at Cuddie Springs in southeastern Australia, assessing relative aridity via oxygen isotopes as well as vegetation and megafaunal diets using both carbon isotopes and dental microwear texture analyses. We report that the Cuddie Springs middle Pleistocene fauna was largely dominated by browsers, including consumers of C4shrubs, but that by late Pleistocene times the C4dietary component was markedly reduced. Our results suggest dietary restriction in more arid conditions. These dietary shifts are consistent with other independently derived isotopic data from eggshells and wombat teeth that also suggest a reduction in C4vegetation after ~45 Ka in southeastern Australia, coincident with increasing aridification through the middle to late Pleistocene. Understanding the ecology of extinct species is important in clarifying the primary drivers of faunal extinction in Sahul. The results presented here highlight the potential impacts of aridification on marsupial megafauna. The trend to increasingly arid conditions through the middle to late Pleistocene (as identified in other paleoenvironmental records and now also observed, in part, in the Cuddie Springs sequence) may have stressed the most vulnerable animals, perhaps accelerating the decline of late Pleistocene megafauna in Australia.

Dental microwear textural analyses to track feeding ecology of reindeer: a comparison of two contrasting populations in Norway

Using dental microwear textural analysis, we aim to explore variations in feeding habits within and between wild reindeer populations (Rangifer tarandus) in Norway. Specimens from the two wild reindeer areas of Knutsho and Hardangervidda were hunted between late August and the end of September 2014, and found to share very similar topological and ecological characteristics (continental alpine tundra). Despite the homogenisation of plant resources at the end of the snow-free period, dental microwear textural analysis on cheek teeth indicates differences in feeding behaviors between the two populations, in that reindeer from Knutsho might display a more “grazing” signal than the ones from Hardangervidda. Such differences in dental microwear textures reflect the differences in feeding habits that could be linked with differences in population density of reindeer. The Knutsho reindeer density is lower than at Hardangervidda, where primary food resources like grasses, sedges, and lichens are less abundant. Analyses also show the differences in gender for the population of Knutsho, but more studies are necessary for the clearest interpretation of data. Our results emphasize the need to explore local variations at a monthly time frame in order to better assess the versatility of dental microwear textures before applying this kind of analysis to either extant or extinct multi-population scales.