Extant Ungulates Research Articles

Paleodietary reconstruction of Equus simplicidens from the Hagerman Horse Quarry (Idaho, USA) highlights high abrasive habits in North American fossil equids during the Pliocene

The evolutionary history of equids represents a paradigmatic case of evolution through time and space when, during the Cenozoic, fossil equids experimented with a variety of forms as well as multiple dietary adaptations. Nowadays, only a single genus of Equidae (Subfamily Equinae, tribe Equini) has survived, Equus, represented by wild zebras and asses and domesticated horses. In this contribution, we undertake a comprehensive mesowear analysis on the Equus simplicidens population from the Hagerman Horse Quarry, Idaho, Pliocene. Our sample includes sixty-two individuals based on crania and maxillae. We used the classic mesowear method in scoring the first or second molar paracone and calculated the average percentages of high versus low relief and sharp versus round versus blunt cusps, but also scored mesowear along a continuum that ranged from sharp cusps with high relief to blunt cusps with low relief by comparing E. simplicidens and extant ungulates. We applied the same methodology to a sample of living zebras, asses and horses to increase our comparative sample. Our results show that the Hagerman E. simplicidens sample had a high-abrasive diet as recorded in the living equid sample, and exhibited no significant distinction between the different age classes sampled. For the first time, these results show that the paleodietary behavior of E. simplicidens was similar to those of the living Equus species.

DIETARY TRAITS OF LATE MIOCENE HIPPARIONS FROM MARAGHEH REVEALED THROUGH DENTAL WEAR

This study investigates the palaeoecology of fossil perissodactyls (equids) from the late Miocene of Maragheh, northwestern Iran. We used dental micro- and mesowear techniques to draw robust inferences about fossil equid paleoenvironment. Mesowear and microwear analyses were applied to the upper molars of three species of hipparionine horses. For this purpose, we investigated samples from three fossiliferous localities: Rohanion, Azim, and Cizdahaban. Six fossil specimens were analyzed for enamel meso- and microwear and results were compared to an extensive database of extant ungulates. Results indicated overlap of the Maragheh hipparions with the dietary signal of extant grazers and grass-dominated mixed feeders. This is consistent with the supposed vegetational habitat proposed by previous mesowear studies. The different species of hipparions from Maragheh had similar diets and were consuming a mixture of plants but with a preference for grasses. These results are consistent with paleoenvironmental reconstructions of the late Miocene dominated by open grassland areas among more wooded settings.

Snout shape and masticatory apparatus of the rodent‐like mesotheriid ungulates (Notoungulata, Typotheria): exploring evolutionary trends in dietary strategies through ancestral reconstructions

AbstractMesotheriidae were small to medium‐sized native South American ungulates. Mesotheriids radiated from the early Oligocene epoch to the early–middle Pleistocene, in two subfamilies: Trachytheriinae and Mesotheriinae. Beyond the conspicuous fossil record, little is known about mesotheriid palaeobiology, and particularly, the dietary habits. To date, different studies suggest grazing habits, similar to some extant ungulates, but recent contributions are challenging this vision. Here, we explore dietary preferences in mesotheriids, focusing on food intake and oral processing strategies. We performed a shape analysis of the snout and reconstructed ancestral shapes to assess evolutionary trends within the clade. Also, we considered other morphological variables of the masticatory apparatus to perform a functional characterization. We recognized three snout configurations: Trachytherus, ‘Intermediate’ and Mesotherium morphotypes that can be associated with different food intake capabilities and, considering other morphological proxies, with the consumption of different food items. Taking into account palaeoenvironmental conditions, the evolution of the masticatory apparatus is interpreted in the context of a consumption gradient from coarse and tough foods (roots, tubers, tough leaves) to grasses. We propose that during the ecomorphological evolution of mesotheriids, an initial phase took place during the late Oligocene and Miocene, consisting of diversification and specialization for consumption of hard‐to‐break food items. A second phase began incipiently during the late Miocene, and became well‐defined during the Pliocene and Pleistocene, characterized by an ecomorphological displacement towards grazing habits. Inferred dietary habits in Mesotheriidae could provide light on palaeoecological evolution and niche partitioning within South American herbivorous mammalian communities.

Wearing down the constraints of low magnification tooth microwear analysis: reproducibility and variability of results based on extant ungulates

Low magnification dental microwear analysis is a widespread dietary proxy for palaeoenvironmental analyses. The limitations of the method, such as observer bias or variation of microwear scars between different tooth positions, are still not quite understood. This study aims to reveal that reproducibility and variability of low magnification dental microwear is better, than it was previously thought. The main focuses of this study were differences between results produced by independent observers, and individual variability of the wear features on different teeth of the same specimen. To approach these issues, the microwear of 1944 0.4 × 0.4 mm areas on every right molar and premolar (144 teeth of 12 extant ungulate specimens) was quantified. Reproducibility and interobserver error was tested by calculating the intraclass correlation coefficients for the scores produced by the observers. The microwear features of each tooth were characterized by the mean, median, standard deviation, range, skewness and kurtosis. These statistical parameters were than compared. To test whether observed differences between the microwear patterns of different tooth positions are significant, ANOVA and Dunnett’s post hoc tests were performed. To calculate the minimal number of sampling sites required for characterizing a tooth, a computer-assisted bootstrap method was applied. As a result, it can be suggested that the low magnification microwear method is quite robust, with low interobserver error. The variance of microwear scars seems uniform throughout the dentition of the examined specimens. Some differences can be noted between tooth positions, however, some limitations could be lifted, at least in the case of ungulates.

Phylogenetic tree of Litopterna and Perissodactyla indicates a complex early history of hoofed mammals

The Litopterna is an extinct clade of endemic South American ungulates that range from Paleocene up to late Pleistocene times. Because of their unique anatomy, litopterns are of uncertain phylogenetic affinities. However, some nineteenth century authors, considered litopterns as related to perissodactyl ungulates, a hypothesis recently sustained by molecular data. The aim of the present contribution is to include litopterns and other South American related taxa in a comprehensive phylogenetic analysis together with several extant and extinct basal perissodactyl ungulates. The analysis resulted in the nesting of litopterns and kin as successive stem-clades of crown Perissodactyla. Further, litopterns are not phylogenetically grouped with any North American basal ungulate, in agreement with some previous proposals. Presence of pan-perissodactyls in South America and India indicates that southern continents probably played an important role in the early evolution of hoofed mammals.

Species delimitation based on diagnosis and monophyly, and its importance for advancing mammalian taxonomy.

A recently proposed taxonomic classification of extant ungulates sparked a series of publications that criticize the Phylogenetic Species Concept (PSC) claiming it to be a particularly poor species concept. These opinions reiteratively stated that (1) the two fundamental elements of the "PSC", i.e., monophyly and diagnosability, do not offer objective criteria as to where the line between species should be drawn; and (2) that extirpation of populations can lead to artificial diagnosability and spurious recognitions of species. This sudden eruption of criticism against the PSC is misleading. Problems attributed to the PSC are common to most approaches and concepts that modern systematists employ to establish species boundaries. The controversial taxonomic propositions that sparked criticism against the PSC are indeed highly problematic, not because of the species concept upon which they are based, but because no evidence (whatsoever) has become public to support a substantial portion of the proposed classification. We herein discuss these topics using examples from mammals. Numerous areas of biological research rest upon taxonomic accuracy (including conservation biology and biomedical research); hence, it is necessary to clarify what are (and what are not) the real sources of taxonomic inaccuracy.

Dietary reconstruction of pygmy mammoths from Santa Rosa Island of California

Microwear analyses have proven to be reliable for elucidating dietary differences in taxa with similar gross tooth morphologies. We analyzed enamel microwear of a large sample of Channel Island pygmy mammoth (Mammuthus exilis) molars from Santa Rosa Island, California and compared our results to those of extant proboscideans, extant ungulates, and mainland fossil mammoths and mastodons from North America and Europe. Our results show a distinct narrowing in mammoth dietary niche space after mainland mammoths colonized Santa Rosa as M. exilis became more specialized on browsing on leaves and twigs than the Columbian mammoth and modern elephant pattern of switching more between browse and grass. Scratch numbers and scratch width scores support this interpretation as does the Pleistocene vegetation history of Santa Rosa Island whereby extensive conifer forests were available during the last glacial when M. exilis flourished. The ecological disturbances and alteration of this vegetation (i.e., diminishing conifer forests) as the climate warmed suggests that climatic factors may have been a contributing factor to the extinction of M. exilis on Santa Rosa Island in the Late Pleistocene.

A tool for determining duration of mortality events in archaeological assemblages using extant ungulate microwear.

The seasonality of human occupations in archaeological sites is highly significant for the study of hominin behavioural ecology, in particular the hunting strategies for their main prey-ungulates. We propose a new tool to quantify such seasonality from tooth microwear patterns in a dataset of ten large samples of extant ungulates resulting from well-known mass mortality events. The tool is based on the combination of two measures of variability of scratch density, namely standard deviation and coefficient of variation. The integration of these two measurements of variability permits the classification of each case into one of the following three categories: (1) short events, (2) long-continued event and (3) two separated short events. The tool is tested on a selection of eleven fossil samples from five Palaeolithic localities in Western Europe which show a consistent classification in the three categories. The tool proposed here opens new doors to investigate seasonal patterns of ungulate accumulations in archaeological sites using non-destructive sampling.

Paleodietary reconstruction of fossil horses from the Eocene through Pleistocene of North America

Paleodietary trends for North American horses from Hyracotherium (early Eocene) through Equus (late Pleistocene) were examined using dental microwear analysis. Over 1200 fossil specimens were analyzed for enamel microwear and results were compared to an extensive microwear database of extant ungulates. This study tests the hypothesis that Eocene horses browsed on low abrasion foods whereas Oligocene and later horses had more abrasive diets concomitant with the spread of more open habitats and examines the correlation between the acquisition of hypsodonty and the beginning of grazing. Microwear results indicate that early to middle Eocene species engaged mostly in fruit browsing. In contrast, late Eocene to Oligocene taxa have microwear scratch numbers typical of grazing and mixed-feeding ungulates, but with very fine scratch textures which are unusual in modern C4 grazers and indicate consumption of relatively low abrasion grasses. An increase in overall dietary abrasion is evident beginning in the early Miocene but members of the Anchitherinae (sensu stricto) engaged in leaf browsing while other forms committed to grazing or alternating between grass and leaves. Anchitherinae (ss) continue to rely on leaves until they became extinct in the late Miocene, while members of the Equinae were either grazing or mixed feeding through the Pleistocene. Dietary abrasion increased further beginning in the late Miocene and continued to increase through the Pleistocene. Most Pleistocene horses were not grazing but rather alternating between grass and leaves or even browsing. Increased pitting of dental enamel and coarser scratch textures in Plio–Pleistocene horses reinforces the idea that increased abrasion may be due to grit encroachment on food items and/or a shift toward coarser grasses than due to a steady increase in the amount of grass consumed.

Comparative dental microwear of ruminant and perissodactyl molars: Implications for paleodietary analysis of rare and extinct ungulate clades

AbstractDental microwear analyses of ungulates and other large herbivores rely on correlations of diet and microwear among extant ungulates, primarily ruminants. Microwear is considered a ‘taxon-free’ method of paleodietary analysis. The properties of food are associated with causality of microwear, but the possibility that heritable properties of the consumer (tooth morphologies, masticatory dynamics, enamel mechanical properties, digestive physiologies) may introduce bias is not considered. Using an observer blind method of light microscopy, we examined the distribution of microwear features on the molars of eight species of ruminants and perissodactyls. Grazing and browsing ruminants had statistically different numbers of scratches forming discrete data clusters. Perissodactyls differ in the numbers of scratches and pits but without discrete browser and grazer clusters. Microwear features were distributed homogeneously across ruminant molars and strongly predictive of diet from the labial edge of the molar to the lingual edge. Microwear was heterogeneously distributed across perissodactyl molars with more pits on the labial edge and more scratches on the lingual edge. In perissodactyls, microwear sampled from the labial edge was strongly predictive of diet, while microwear sampled from other areas were not. Discriminant function analyses of microwear assigned individual molars to diets (browser and grazer) and clades (ruminant and perissodactyl) with similar success (70–73%) indicating that phylogeny and diet influence microwear equally. Rhino microwear was more sensitive to clade membership while other perissodactyl microwear was more sensitive to diet. Although it is not clear what heritable variables may phylogenetically bias dental microwear, extant ruminants may not be appropriate models for the microwear of other large herbivores.

Maragheh Ungulate Mesowear: Interpreting Paleodiet and Paleoecology from a Diverse Fauna with Restricted Sample Sizes

This study explores the extent to which researchers might be able to interpret a fauna's paleoecology using mesowear analysis on ungulate maxillary molars when there are diverse taxa represented by few specimens. We compared our mesowear results on Maragheh ungulates with those of extant ungulates and with known mesowear score distributions of the two classical Greek Pikermian faunas of Samos and Pikermi, and with the late Miocene of China. The Maragheh equid and bovid species display a range of dietary abrasiveness, whereas the giraffids and chalicothere have fairly abrasive mesowear signals. Despite small sample sizes for some taxa, our results are consistent with long-held taxon-based interpretations of Maragheh paleoecology: a Pikermian woodland habitat. In addition, our results are consistent with climatic changes of the Paratethyan realm at the end of the Miocene.

The Inter-Relationship between Dietary and Environmental Properties and Tooth Wear: Comparisons of Mesowear, Molar Wear Rate, and Hypsodonty Index of Extant Sika Deer Populations

In reference to the evolutionary trend of increasing cheek tooth height in herbivorous ungulates, the causes of dental abrasion have long been debated. Interspecific comparisons of extant ungulates have revealed that both phytoliths in grass and external abrasive matter may play important roles. Using analysis of extant sika deer living in various environments and showing continuous latitudinal variation in food habits from northern grazing to southern browsing, we quantitatively evaluated the influence of dietary and environmental properties on three dental variables: mesowear score (MS), molar wear rate, and M3 hypsodonty index. We used 547 skulls and 740 mandibles from 16 populations of sika deer to obtain the dental measurements. We found that only graminoid proportion in diet correlated with MS and the molar wear rate, implying that phytoliths in grass abrade dental tissues. In contrast, annual precipitation in habitat was not correlated with any of the dental variables. We also found a significant correlation between the molar wear rate (selective pressure for high-crowned molars) and the M3 hypsodonty index of extant sika deer, implying an evolutionary increment in molar height corresponding to the molar wear rate. Our intraspecific comparative analyses provide further support for use of mesowear analysis as a paleodiet estimation method; it not only reveals staple food types (graminoids or dicots) but also implies regional or seasonal variation in the diet of the species.

Critical revision of the alleged delayed dental eruption in South American “ungulates”

The endemic South American “ungulates” (SANU) were traditionally assumed to be a monophyletic offshoot of the Granorder Ungulata, but the current reorganization of the extant ungulates in Laurasiatheria and Afrotheria (based on molecular data) leaved them in an undetermined systematic position. The delayed dental eruption versus cranial growth was proposed as a hard-tissue synapomorphy of Afrotheria. In a recent paper, at least some endemic SANU (Notoungulata, Astrapotheria, and possibly Pyrotheria) were interpreted as allied to Afrotheres by having a late replacement of deciduous cheek teeth. This statement was based on: (1) the usual occurrence within these groups of individuals with deciduous and permanent teeth; (2) the individual size (estimated comparing the length/width ratio of cheek teeth) of specimens with permanent premolars erupted is indistinguishable from that of specimens with deciduous premolars (putative juveniles), and (3) the retention of at least dP1–dP3 in adult specimens of Parastrapotherium (Astrapotheria). Herein we critically examine the presumed existence of delayed dental eruption in astrapotheres, pyrotheres and xenungulates and the assumptions on which it was based. The alleged evidences supporting the occurrence of delayed dental eruption in SANU arise from misinterpreted information from the literature and conceptual mistakes (i.e. delayed dental eruption versus cranial growth was confused with delayed replacement of premolars versus molar eruption). Based on examination of at-hand specimens, we found that there is no evidence for a delayed premolar replacement relative to the eruption of the molars in astrapotheres, pyrotheres, and xenungulates. A delayed dental eruption in relation to jaw growth does not occur at least in Astrapotherium magnum. Although a very recent study proposed close relationships among afrotheres and at least notoungulates and xenungulates, a more complete analysis is still needed to elucidate the evolutionary relationships of astrapotheres and pyrotheres.

Effects of Dietary Differences between Sympatric Japanese Serow and Sika Deer on Environmental Reconstruction by Means of Mesowear Analysis

Diet reconstruction using mesowear analysis has mainly been applied to extinct species and their paleoenvironments. Little is known regarding the effects of dietary differences on sympatric environments using this analysis and the limited existing knowledge from extant species may introduce errors when applied to fossil assemblages. I aimed to determine the sensitivity of mesowear analysis using extant ungulates with known diets. An interspecific comparison was conducted using wild populations of Japanese serow (Capricornis crispus, n = 37) and sika deer (Cervus nippon, n = 55) living in deciduous broad-leaved forest of the Nikko National Park, central Japan. One of the mesowear variables differed significantly between the two species (Fisher's exact test: p < 0.05). According to hierarchical cluster and principal component analyses, Japanese serow were classified as browsers, while sika deer as mixed feeders. Previous studies support these results; therefore, mesowear analysis can be used to detect dietary differences in sympatric species.

Distributions of cranial pathologies provide evidence for head-butting in dome-headed dinosaurs (Pachycephalosauridae).

Pachycephalosaurids are small, herbivorous dinosaurs with domed skulls formed by massive thickening of the cranial roof. The function of the dome has been a focus of debate: the dome has variously been interpreted as the product of sexual selection, as an adaptation for species recognition, or as a weapon employed in intraspecific combat, where it was used in butting matches as in extant ungulates. This last hypothesis is supported by the recent identification of cranial pathologies in pachycephalosaurids, which appear to represent infections resulting from trauma. However, the frequency and distribution of pathologies have not been studied in a systematic fashion. Here, we show that pachycephalosaurids are characterized by a remarkably high incidence of cranial injury, where 22% of specimens have lesions on the dome. Frequency of injury shows no significant difference between different genera, but flat-headed morphs (here interpreted as juveniles or females) lack lesions. Mapping of injuries onto a digitial pachycephalosaurid skull shows that although lesions are distributed across the dome, they cluster near the apex, which is consistent with the hypothesis that the dome functioned for intraspecific butting matches.

Occlusal enamel complexity and its implications for lophodonty, hypsodony, body mass, and diet in extinct and extant ungulates

Tooth morphology and rates of wear have strong controls on how well mammals survive in their habitats. Herbivorous mammals, specifically ungulates, combat the effects of wear through a combination of changing the occlusal (chewing surface) enamel length, and changing hypsodonty (relative height of tooth). Changes in these two attributes are most notably seen in the fossil record of ungulates as they adapted to living in cooler, drier, and more open habitats. We expect enamel length and hypsodonty to be greater in ungulate taxa that feed on grasses than in non-grass feeders. We tested this hypothesis by digitally photographing 213 maxillary tooth rows from 84 species of extinct and extant ungulates (n=1083 teeth) and measuring their occlusal enamel length and true occlusal area. We then statistically compared the influences of taxonomy, feeding strategy, tooth position, and tooth area on both hypsodonty and occlusal enamel length using principal components analysis (PCA) and a nested multivariate analysis of variance (MANOVA). The results of our PCA indicated a strong correlation between enamel length and tooth area, but little correlation of either with hypsodonty. Our nested MANOVA showed that tooth position had no significant relationship with hypsodonty (p=0.1539), while all other factors were significant for both hypsodonty and occlusal enamel length. Our results suggest that the occlusal enamel length in ungulate teeth is constrained by both the size of the tooth (and, by proxy, the mass of the individual) and diet. Absolute tooth crown height is similarly affected by a combination of body size and diet, leading to the use of a ratio, hypsodonty index, to characterize the diet component. We propose a similar ratio, the occlusal enamel index (OEI) which reduces the effect of body mass to clearly indicate the component of enamel length determined by abrasiveness of ingested material.

Dietary ecology of extant guanaco (Lama guanicoe) from Southern Patagonia: seasonal leaf browsing and its archaeological implications

The analysis of dietary traits of ungulates through tooth microwear and mesowear has been applied to archaeological sites to investigate seasonal changes in settlements by hunter–gatherers. In this paper we propose to test the hypothesis that tooth microwear (combined to mesowear) is able to indicate seasonality in the diet of extant ungulates in arid habitats (semi-deserts or steppe). The material analyzed comes from six faunal monospecific assemblages of guanaco (Lama guanicoe) resulting from a mass mortality event in winter 2000 near the Cardiel Lake in Southern Patagonia (Province of Santa Cruz, Argentina). Mesowear results indicate that the guanacos from the Cardiel Lake area are mixed feeders, and thus, have a diet that shifts seasonally. Moreover, microwear analysis supports the hypothesis that tooth microwear is able to indicate seasonality in the diet of extant guanaco in arid habitats. The pattern is clear for the winter sample and needs to be confirmed for a summer sample. Consequently, tooth microwear is proposed as a new potential proxy for detecting seasonal occupation in archaeological sites in Patagonia and other arid environments.

The occurrence of an abdominal fauna in an articulated tapir (Tapirus polkensis) from the Late Miocene Gray Fossil Site, northeastern Tennessee

The analysis of samples recovered from the abdominal area of an articulated tapir (Tapirus polkensis) from the Late Miocene (4.5-7 million BP) Gray Fossil Site (GFS) revealed a rich palyno-fauna comprised of about 94% egg/oocyst-like structures and 6% pollen and other palynomorphs. In addition, a group of 6 hickory nuts (Carya) was recovered from the same area suggesting that the samples represent the abdominal contents. The analysis of a sample from immediately outside the tapir produced a sample with 98% pollen and less than 0.5% egg/oocyst-like structures. The size, shape, and general morphology of egg/oocyst-like structures were analyzed with light and scanning electron microscopy and were compared to a variety of intestinal parasites found in extant ungulates, and the Perissodactyla in particular. We also compared fossil structures to the numbers and kind of intestinal parasites recovered from fecal samples from the Baird's tapir (T. bairdii) in Costa Rica and from samples collected from the lowland tapir (T. terrestris) from Ecuador to assess their similarity to our fossil sample. Based on these data, we discuss what role parasites may have played in the biology of T. polkensis during the Late Miocene-Early Pliocene.

Body mass estimation in Early Miocene native South American ungulates: a predictive equation based on 3D landmarks

AbstractSouth American native ungulates include extinct taxa that evolved within the geographical context given by the isolation of South America during most of the Cenozoic. The ungulates (orders Notoungulata, Litopterna and Astrapotheria) of the Santa Cruz Formation (late Early Miocene) are particularly interesting for paleobiological studies due to their diversity, richness and quality of preservation of the specimens. The body mass estimation of extinct species is one of the basic biological attributes for paleobiological reconstructions. The most common way to estimate body mass from fossils is using linear regression. Here, we used geometric morphometric techniques in order to estimate their body mass. We used regressions based on centroid size of 3D craniomandibular landmark configurations, including extant ungulates (their size and ecological relatives). Cases were weighted to maximize the taxonomic evenness. A broad body size range was recorded. The highest predictive power is obtained with those functions derived from the highest taxonomic and ecological diversity. The highest taxonomic richness corresponds to masses below 100 kg. Among Notoungulata, typotheres (Hegetotheriidae + Interatheriidae) vary from 1 to less than 10 kg, while the smaller toxodontid reached 100 kg and the larger 500 kg. Litoptern proterotheriid body masses vary from 10 to 50 kg, and macraucheniids surpass 100 kg. The astrapotheres (Astrapotheria) reached (or even surpassed) 1000 kg, being the only megamammal in the Santacrucian ungulate assemblage.

Ancient diet of the Pleistocene gomphothere Notiomastodon platensis (Mammalia, Proboscidea, Gomphotheriidae) from lowland mid-latitudes of South America: Stereomicrowear and tooth calculus analyses combined

The gomphothere assemblage from the Pleistocene of Águas de Araxá (Minas Gerais State, Brazil) is composed of several isolated teeth, cranial and postcranial fragments assigned to a single population of Notiomastodon platensis. The age profile suggests decline of the population, due to the large amount of senile and mature adult individuals. The mortality event probably occurred during a long period of low humidity, which could cause a mass death of the proboscideans around water refuges. The ancient feeding ecology of these gomphotheres was reconstructed through stereomicrowear and plant microfossils from teeth calculi, using molars from four age classes. The enamel microwear patterns were recognized according to published studies, whereas the average scratch and pit values were compared to an extant ungulates database. The plant microfossils were chemically recovered and microscopically analyzed. Isotopic analyses of the South American gomphotheres suggest a wide dietary range for N. platensis, except for two localities: Santiago del Estero (Argentina) and La Carolina (Ecuador). For these, isotope analyses suggested an exclusive C4 diet, whereas all other South American localities studied so far indicate an exclusive C3 diet or a mixed C3 and C4 diet. The results also support the apparent latitudinal gradient of C3/C4 grasses. The stereomicrowear analyses for N. platensis exhibited average scratch and pit values, which places it within the extant mixed-feeder morphospace. The higher frequency of fine scratches indicated the ingestion of C3 grasses. Alternatively, the presence of coarse and hypercoarse scratches along with gouges and large pits suggested the ingestion of foliage and lignified portions. The plant microfossil analysis recovered fragments of a conifer tracheid and vessel elements with a ray of parenchyma cells, which corroborates the consumption of wood plants. Also, pollen grains (Polygonaceae), spores (Polypodiaceae) and fibers were found in the samples. According to the results, the Águas de Araxá gomphotheres were feeding generalists and consumed wood elements, leaves and C3 grasses.