Dental Microwear Texture Analysis Research Articles

Dental wear at macro- and microscopic scale in rabbits fed diets of different abrasiveness: A pilot investigation

To differentiate the effects of internal and external abrasives on tooth wear, we performed a controlled feeding experiment in rabbits fed diets of varying phytolith content as an internal abrasive and with addition of sand as an external abrasive. 13 rabbits were each fed one of the following four pelleted diets with different abrasive characteristics (no phytoliths: lucerne L; phytoliths: grass G; more phytoliths: grass and rice hulls GR; phytoliths plus external abrasives: grass, rice hulls and sand GRS) for two weeks. At the end the feeding period, three tooth wear proxies were applied to quantify wear on the cheek teeth at macroscopic and microscopic wear scales: CT scans were obtained to quantify tooth height. Mesowear was scored adapted to this species, and 3D dental microwear texture analysis (DMTA) was performed on four antagonistic teeth. Both external and internal abrasives resulted in increased wear in all proxies compared to the phytolith and sand-free diet (L). The wear effect was more prominent on the maxillary than on the mandibular teeth. On the GRS diet, the upper third premolar had the largest decline in relative tooth height compared to others in the same tooth row. The impact of diet abrasiveness on the mesowear signal was only clearly visible for the most abrasive diet, most likely due to the limited sample size. DMTA was especially sensitive to phytolith changes in the diet, and surface roughness generally increased with increasing amounts of abrasive agents (L < G < GR < GRS) as expressed in an increase of most height and volume parameters. The fast pace of dental wear in this species led to some expected correlations between tooth height, mesowear and DMTA parameters, creating a distinct wear pattern for each diet. Animal models with high wear rates may be particularly suitable for investigations on functional interrelationships of different wear proxies.

Clarifying relationships between cranial form and function in tapirs, with implications for the dietary ecology of early hominins

Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e. hard-object feeding), many primates with similar morphologies consume an array of tough and hard foods—complicating dietary inferences of early hominins. We posit that tapirs, large herbivorous mammals showing variable sagittal crest development across species, are ideal models for examining correlations between textural properties of food and sagittal crest morphology. Here, we integrate dietary data, dental microwear texture analysis, and finite element analysis to clarify the functional significance of the sagittal crest in tapirs. Most notably, pronounced sagittal crests are negatively correlated with hard-object feeding in extant, and several extinct, tapirs and can actually increase stress and strain energy. Collectively, these data suggest that musculature associated with pronounced sagittal crests—and accompanied increases in muscle volume—assists with the processing of tough food items in tapirs and may yield similar benefits in other mammals including early hominins.

Exploring the utility of optical microscopy versus scanning electron microscopy for the quantification of dental microwear

Dental microwear has been used for the reconstruction of diet for decades, and given its long history, substantial changes in the methodologies and technologies used to observe and quantify microwear have occurred. For instance, early work on microwear used optical microscopy (OM), before being largely replaced by scanning electron microscopy (SEM). More recently, SEM-based studies have been overshadowed by confocal microscopy and dental microwear texture analysis. However, SEM is still the preferred method of data acquisition for buccal microwear analysis and significant improvements in OM have also occurred in recent years – particularly with the development of continuous focus systems for OM. Given the low-cost and simple upkeep of OM compared to SEM, this study seeks to explore the utility of OM for buccal microwear data acquisition compared to the methods established using SEM. A sample of 18 human teeth (originals and casts) were analyzed using both OM and SEM. Results show that more striations are observed using OM than when analyzing the same surface with SEM. However, the central counting trend is similar with both techniques. We can therefore conclude that OM is a consistent and user-friendly method that provides good image resolution together with a series of economic and technical advantages.

Everything matters: Molar microwear texture in goats (Capra aegagrus hircus) fed diets of different abrasiveness

There is an ongoing discourse about whether or not external abrasives influence the microscopic wear in herbivore teeth, including a statement that “dust does not matter”. We submitted the maxillary and mandibular second molar of 28 goats (Capra aegagrus hircus) to dental microwear texture analysis (DMTA). The study animals were divided into four groups, which received diets of increasing phytolith-based abrasiveness (L: lucerne based pellets, very low phytolith abrasion diet, acting as control; G: grass-based pellets, medium abrasive phytolith diet; GR: grass and rice husk pellets, high abrasion phytolith diet), or a diet with added external abrasives (GRS: the GR diet with addition of large-grained sand as source of external abrasives), for 6 months. Generally, the three diets without sand (L, G, GR) were ranked in the expected sequence by DMTA parameters. For some parameters, in particular those relating to area, complexity, peak sharpness and plateau size of the enamel surface, diet GRS differed from diet GR, whereas the two were not distinct in other parameters, mostly relating to direction, height or volume. Additionally, diets triggered different patterns on the maxillary or mandibular molar for several parameters. For some DMTA parameters, the range covered in the experimental goats corresponded to that observed in free-ranging browsing giraffe (Giraffa camelopardalis) and grazing wildebeest (Connochaetes taurinus), with goats receiving diet L resembling the giraffe, while the other diets G, GR and GRS more resembled the wildebeest. However, the previously reported mesowear in the goats did not cover the browser-grazer range, and DMTA measurements showed no correlation to the development of mesowear scores or measures of absolute tissue loss in the same animals. In summary, the results confirm DMTA measurements as generally recording properties related to both internal and external abrasives, but also indicate that our understanding of how DMTA characteristics actually originate, and how they relate to other proxies of dental wear, is still very limited.

Methodological implications of intra- and inter-facet microwear texture variation for human childhood paleo-dietary reconstruction: Insights from the deciduous molars of extant and medieval children from France

The present study concerns occlusal dental microwear texture variation on the deciduous molars of children. A description and evaluation of microwear texture variation within facet 9 and a comparison of microwear textures between grinding facets 9 and 11 are presented. The relationship between wear facet surface area and intra-facet microwear texture variability is evaluated. The sample is composed of naturally-exfoliated, taphonomy-free deciduous second molars from twelve extant children and four archaeologically-derived medieval children (for a total of 51 surface measurements). Dental microwear texture analysis (DMTA) was performed using a confocal microscope and scale-sensitive fractal analysis (SSFA) at three standardized locations on facet 9, and one location on facet 11. Facet shape was visually assessed and scored using a headset magnifier (3×) and composite images (20× confocal microscopy). Individuals were assigned to two groups based on a qualitative assessment of facet surface area. Microwear texture variability within facet 9 was high relative to the variability of microwear textures between individuals. No significant inter-facet variation between facets 9 and 11 was detected. No clear differences in microwear and variabilities within facet 9 were found between individuals assigned to small and large facet groups. Our study shows the existence of important intra-facet microwear variation in a sample of children. Intra-facet microwear variation can affect the ability of DMTA to distinguish between diets in contexts with small sample sizes and subtle differences in diet – such as those characterizing dietary transitions in children. Results also suggest non-dietary factors may influence microwear formation during dental exfoliation. A better understanding of intra-facet microwear variation, and when and how to account for it, can improve the application of occlusal DMTA in similar contexts.

Discriminating management strategies in modern and archaeological domestic caprines using low-magnification and confocal dental microwear analyses

Dental Microwear Analysis (DMA) is currently used for obtaining information on diet of different animal species. Low-magnification Microwear Dental Analysis (LMDA) is a DMA technique based on the identification of microfeatures (pits and scratches) on the tooth enamel surface. During the last decade, Dental Microwear Texture Analysis (DMTA) has gained momentum as an alternative quantitative methodology thus offering more reliable and replicable results and allowing highlighting subtle dietary differences. In this paper we explore the capacities of LMDA and DMTA for discriminating flock managing strategies. Two groups of sheep that were fed differently during the last month of life, one roaming on rangeland, combining Mediterranean forest and meadows and the other on grassland were analysed. While LMDA did not allow discriminating both groups, DMTA showed significant differences between them. DMTA revealed good predictive capacity for the correct classification of the individuals grazing on grasslands, and a poor one for the ones grazing on rangeland, as some of them overlapped with the grassland group. The limitation for correctly classifying roaming individuals is probably explained by the variable composition of plants on rangeland. We used the classificatory rule obtained from the experimental program to classify two archaeological collections of caprines (sheep and goats), from two Iron Age sites from the north-east of the Iberian Peninsula: The Iberian site of El Turó de la Font de la Canya and the Greek colony of Empúries. Finally, we compared the results with those obtained in previous studies using low-magnification microwear techniques (LMDA). In this way, we show the potential of DMTA for discriminating between animal feeding strategies in the past.

Invasive species, not environmental changes, restrict the population and geographical range of the quokka (Setonix brachyurus)

AbstractEuropean arrival into Australia had large‐scale impacts on the local flora and fauna. Most notably, Europeans brought with them numerous non‐native species, including the European red fox (Vulpes vulpes), European rabbit (Oryctolagus cuniculus), and the goat (Capra hircus) among many others. The introduction of these species had significant consequences on native Australian mammals, causing some small‐ to medium‐sized herbivores to become geographically restricted to primarily islands. Here, we examined the dietary ecology of the quokka (Setonix brachyurus), a native marsupial herbivore with a restricted geographic range in Western Australia before and after European arrival. Fossils from south‐western Australia and modern specimens were examined via dental microwear texture analysis and stable isotope analysis to assess whether the diet of the quokka had changed dramatically over time. Collectively, we help clarify whether there were any ecological reasons as to why this marsupial became geographically restricted, aside from the presence of invasive predators on mainland Australia. The quokka maintains a browsing diet from the Pleistocene to the present on the mainland, but modern island populations eat drier and tougher foods when living on islands lacking invasive mammals. There is also an apparent shift in the feeding environment of the quokkas on mainland Australia, from more open forests/shrublands in the Pleistocene to denser and wetter forests. Multi‐proxy data collectively indicate that the restricted range of the quokka today is most likely a result of predation from non‐native taxa and/or other human influences—not because of a lack of suitable habitat.

Dental microwear as a behavioral proxy for distinguishing between canids at the Upper Paleolithic (Gravettian) site of Předmostí, Czech Republic

Morphological and genetic evidence put dog domestication during the Paleolithic, sometime between 40,000 and 15,000 years ago, with identification of the earliest dogs debated. We predict that these earliest dogs (referred to herein as protodogs), while potentially difficult to distinguish morphologically from wolves, experienced behavioral shifts, including changes in diet. Specifically, protodogs may have consumed more bone and other less desirable scraps within human settlement areas. Here we apply Dental Microwear Texture Analysis (DMTA) to canids from the Gravettian site of Předmostí (approx. 28,500 BP), which were previously assigned to the Paleolithic dog or Pleistocene wolf morphotypes. We test whether these groups separate out significantly by diet-related variation in microwear patterning. Results are consistent with differences in dietary breadth, with the Paleolithic dog morphotype showing evidence of greater durophagy than those assigned to the wolf morphotype. This supports the presence of two morphologically and behaviorally distinct canid types at this middle Upper Paleolithic site. Our primary goal here was to test whether these two morphotypes expressed notable differences in dietary behavior. However, in the context of a major Gravettian settlement, this may also support evidence of early stage dog domestication. Dental microwear is a behavioral signal that may appear generations before morphological changes are established in a population. It shows promise for distinguishing protodogs from wolves in the Pleistocene and domesticated dogs from wolves elsewhere in the archaeological record.

Dental microwear texture analysis and diet in caviomorphs (Rodentia) from the Serra do Mar Atlantic forest (Brazil)

AbstractThe Serra do Mar Atlantic forest (Brazil) shelters about 15 different species of caviomorph rodents and thus represents a unique opportunity to explore resource partitioning. We studied 12 species with distinct diets using dental microwear texture analysis (DMTA). Our results revealed differences (complexity, textural fill volume, and heterogeneity of complexity) among species with different dietary preferences, and among taxa sharing the same primary dietary components but not those with similar secondary dietary preferences (heterogeneity of complexity). We found three main dietary tendencies characterized by distinct physical properties: consumers of young leaves had low complexity; bamboo specialists, fruit and seed eaters, and omnivorous species, had intermediate values for complexity; grass, leaf, and aquatic vegetation consumers, had highly complex dental microwear texture. Dietary preferences and body mass explained a major part of the resource partitioning that presumably enables coexistence among these rodent species. DMTA was useful in assessing what foods contributed to resource partitioning in caviomorphs. Our database for extant caviomorph rodents is a prerequisite for interpretation of dental microwear texture of extinct caviomorph taxa, and thus for reconstructing their diets and better understanding the resource partitioning in paleocommunities and its role in the successful evolutionary history of this rodent group.

Dust and grit matter: abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (Ovis aries).

External abrasives ingested along with the herbivore diet are considered main contributors to dental wear, though how the different sizes and concentrations of these abrasives influence wear remains unclear. Dental microwear texture analysis (DMTA) is an established method for dietary reconstruction which describes a tooth's surface topography on a micrometre scale. The method has yielded conflicting results as to the effect of external abrasives. In the present study, a feeding experiment was performed on sheep (Ovis aries) fed seven diets of different abrasiveness. Our aim was to discern the individual effects of size (4, 50 and 130 µm) and concentration (0%, 4% and 8% of dry matter) of abrasives on dental wear, applying DMTA to four tooth positions. Microwear textures differed between individual teeth, but surprisingly, showed no gradient along the molar tooth row, and the strongest differentiation of experimental groups was achieved when combining data of all maxillary molars. Overall, a pattern of increasing height, volume and complexity of the tooth's microscopic surface appeared with increasing size of dietary abrasives, and when compared with the control, the small abrasive diets showed a polishing effect. The results indicate that the size of dietary abrasives is more important for dental microwear texture traces than their concentration, and that different sizes can have opposing effects on the dietary signal. The latter finding possibly explains conflicting evidence from previous experimental DMTA applications. Further exploration is required to understand whether and how microscopic traces created by abrasives translate quantitatively to tissue loss.

Why should traceology learn from dental microwear, and vice-versa?

Dental and artifact microwear analyses have a lot in common regarding the questions they address, their developmental history and their issues. However, few paleontologists and archeologists are aware of this, and even those who are, do not take into account most of the methodological insights from the other field.In this focus article, we briefly review the main developmental steps of both methods, highlight how similar their histories are and how combining methodological developments can improve both research fields. In both cases, the traditional analyses have been strongly criticized mainly because of their subjectivity and their lack of repeatability and reproducibility. Quantitative surface texture analyses have been proposed in response, resulting in dental microwear texture analysis (DMTA) and quantitative artifact microwear analysis (QAMA). DMTA is however a more mature method than QAMA and is well supported within the paleontological community.In this paper, focused on the methodological framework of both fields, we address this topic by arguing that traceologists could borrow a lot from DMTA; this would allow QAMA to become an established method much more quickly. Dental microwear analysts can also learn from traceology, especially regarding sample preparation, experimentation and residue analysis.We hope that this focus article will stimulate more awareness, exchange and collaboration between paleontologists and archeologists, and especially between dental and artifact microwear analysts. Paleontology, archeology and the field of surface analysis as a whole would all benefit from such cooperation.

Dietary reconstruction of Spy I using dental microwear texture analysis

Spy I from the Meuse River Basin of Belgium is among the most recent Neandertals. This adult lived at the terminus of Marine Isotope Stage (MIS) 3 in cold steppe environments at the northern edge of the habitable zone for Neandertals where plants were relatively scarce. The dietary proclivities of Spy I are reconstructed using dental microwear texture analysis and compared to 33 Neandertals from western Eurasia, MIS 5 to MIS 3. Spy I has an elevated enamel surface complexity suggesting the consumption of course dietary items such as wild seeds, acorns, nuts, and underground storage organs laden with particles of grit. Unlike the young and old individuals from Hortus with low values for anisotropy, Spy I is closest to the adults from this site suggesting a common pattern of masticatory behavior typified this life cycle stage. Like many other Neandertals, Spy I probably consumed plant foods at appreciable levels, some of which were hard and brittle or poorly processed.

Dietary differences in archosaur and lepidosaur reptiles revealed by dental microwear textural analysis

Reptiles are key components of modern ecosystems, yet for many species detailed characterisations of their diets are lacking. Data currently used in dietary reconstructions are limited either to the last few meals or to proxy records of average diet over temporal scales of months to years, providing only coarse indications of trophic level(s). Proxies that record information over weeks to months would allow more accurate reconstructions of reptile diets and better predictions of how ecosystems might respond to global change drivers. Here, we apply dental microwear textural analysis (DMTA) to dietary guilds encompassing both archosaurian and lepidosaurian reptiles, demonstrating its value as a tool for characterising diets over temporal scales of weeks to months. DMTA, involving analysis of the three-dimensional, sub-micrometre scale textures created on tooth surfaces by interactions with food, reveals that the teeth of reptiles with diets dominated by invertebrates, particularly invertebrates with hard exoskeletons (e.g. beetles and snails), exhibit rougher microwear textures than reptiles with vertebrate-dominated diets. Teeth of fish-feeding reptiles exhibit the smoothest textures of all guilds. These results demonstrate the efficacy of DMTA as a dietary proxy in taxa from across the phylogenetic range of extant reptiles. This method is applicable to extant taxa (living or museum specimens) and extinct reptiles, providing new insights into past, present and future ecosystems.

Dental Microwear Texture Analysis in Two Ruminants, Japanese Serow (Capricornis crispus) and Sika Deer (Cervus nippon), from Central Japan

Dental microwear texture analysis (DMTA) can be used to quantitatively evaluate tooth surface roughness and has been used to distinguish herbivorous ungulates according to interspecific dietary differences among grazers, browsers, and mixed feeders. Moreover, DMTA has been applied among local populations with intraspecific dietary variation. In general, the tooth surfaces of grazing species/populations are rough, whereas those of browsing species/populations are smooth. Whether DMTA can be used to detect dietary differences among sympatric species is of interest. In the present study, we aimed to use DMTA to explore interspecific differences in diet between two ruminants in Japan—the sika deer and Japanese serow in Nagano Prefecture. We found significant differences in surface roughness parameters between deer and serow. The tooth surfaces of the deer were more undulated with parallel scratches, whereas those of the serow were smoother with pits. These results indicate that the deer consumed abrasive graminoids more frequently than the serow, which is in accordance with previous dietary analyses. However, the two species did not segregate dichotomously but showed a huge overlap in DMTA parameters, implying dietary overlap. The present study shows the potential of DMTA to clarify the foraging ecology of sympatric ruminants from skeletal specimens.

Dental microwear texture analysis of Pliocene Suidae from Hadar and Kanapoi in the context of early hominin dietary breadth expansion

Stable carbon isotope studies suggest that early hominins may have diversified their diet as early as 3.76 Ma. Early Pliocene hominins, including Australopithecus anamensis, had diets that were dominated by C3 resources while Late Pliocene hominins, including Australopithecus afarensis—a putative descendant of A. anamensis—had diets that included both C3 and C4 resources. It has been hypothesized that the expansion of C4 grasslands in eastern Africa during the Pliocene could have prompted hominins to incorporate C4 resources in their diets. However, dental microwear analyses suggest that diet diversification did not involve changes in the mechanical properties of the foods consumed. To provide contextual and comparative information on this issue, the diet of suids from the A. anamensis site of Kanapoi and the A. afarensis site of Hadar is investigated. Using dental microwear texture analyses, it is shown that despite significant dietary overlap, there is evidence for dietary niche partitioning among suids. Based on comparisons with the diet of extant African suids, it is inferred that Nyanzachoerus pattersoni (n = 21) was a mixed feeder, Nyanzachoerus jaegeri (n = 4) and Notochoerus euilus (n = 61) were habitual grazers, and Kolpochoerus afarensis (n = 34) had a broad diet that included hard brittle foods and underground resources. The dental microwear of Ny. pattersoni and Ny. jaegeri/No. euilus do not differ significantly between Kanapoi and Hadar. Most differences are driven by K. afarensis, a suid absent at Kanapoi but present at Hadar. Food availability probably differed between Hadar and Kanapoi, and it is likely that A. afarensis did not exploit some of the foods (e.g., underground resources) consumed by suids. It is hypothesized that despite the incorporation of C4 resources in the diet, a significant dietary change towards flexible diets in the hominin lineage had yet to come.

Incorporating intraspecific variation into dental microwear texture analysis.

Dental microwear texture analysis (DMTA) quantifies microscopic scar or wear patterns left on teeth by different foods or extraneous ingested items such as grit. It can be a powerful tool for deducing the diets of extinct mammals. Here we investigate how intraspecific variation in the dental microwear of macropodids (kangaroos and their close relatives) can be used to maximize the dietary signal inferable from an inherently limited fossil record. We demonstrate significant intraspecific variation for every factor considered here for both scale-sensitive fractal analysis and International Organization for Standardization surface texture analysis variables. Intraspecific factors were then incorporated into interspecific (dietary) analyses through the use of Linear Mixed Effects modelling, incorporating Akaike's Information Criterion to compare models, and testing models through independent cross-validation. This revealed that for each DMTA variable only a small number of intraspecific factors need to be included to improve differentiation between species. Including specimen as a random factor accounted for stochastic inter-individual variation, and facet, incorporated effects of sampling location. Intraspecific effects of ecoregion, microscope, tooth position and wear were often but not universally important. We conclude that models of microwear data that include intraspecific variation can improve the resolution of dietary reconstructions.

Dental microwear textures and dietary preferences of extant rhinoceroses (Perissodactyla, Mammalia)

Rhinoceroses were conspicuous elements in Cenozoic ecosystems, and studying the ecological behavior of extant species might unravel the ecology of their fossil kin. Microwear as a short-term recorder may detect subtle variations in the diet. Dental microwear texture analysis (DMTA) is extensively used to infer paleodiets. Yet, regarding ungulates, most microwear studies have been conducted on artiodactyls, and more particularly on ruminants (i.e., foregut fermenters), which may not be good models for hindgut fermenters, such as rhinoceroses. Moreover, rhinoceroses display a specific enamel ultrastructure with vertical Hunter–Schreger bands and a peculiar mastication cycle likely to impact tooth response to wear. Here, we studied the DMTA of the five extant rhinoceros species (17 specimens of Ceratotherium simum, four of Dicerorhinus sumatrensis, 21 of Diceros bicornis, 14 of Rhinoceros sondaicus, and 5 of Rhinoceros unicornis) and built up the present dataset. In parallel, we also compiled a taxon-based dataset of consumed plants for each rhinoceros species. Accordingly, we propose to reclassify the Indian rhinoceros (Rhinoceros unicornis) from mixed-feeder to variable grazer. Significant discrepancies were found between grinding and shearing facets on molars and between species on a given facet. Plotting the percentage of anisotropic specimens against that of complex specimens for each species discriminated well the different diets on both facets. This unprecedented dataset on rhinoceros texture microwear confronted to detailed diets appears critical for future diet reconstruction of fossil rhinocerotoids.

Dental microwear texture analysis of Homo sapiens sapiens: Foragers, farmers, and pastoralists.

The current study seeks to determine if a sample of foragers, farmers, and pastoralists are distinguishable based on their dental microwear texture signatures. The study included a sample of 719 individuals from 51 archeological sites (450 farmers, 192 foragers, 77 pastoralists). All were over age 12 and sexes were pooled. Using a Sensofar® white-light confocal profiler we collected dental microwear texture analysis (DMTA) data from a single first or second molar from each individual. We leveled and cleaned data clouds following standard procedures and analyzed the data with Sfrax® and Toothfrax® software. The DMTA variables were complexity and anisotropy. Statistics included ANOVA with partial eta squared and Hedges's g. We also performed a follow-up K-means cluster analysis. We found significant differences between foragers and farmers and pastoralists for complexity and anisotropy, with foragers having greater complexity than either the farmers or the pastoralists. The farmers and pastoralists had greater anisotropy than the foragers. The Old World foragers had significantly higher anisotropy values than New World foragers. Old and New World farmers did not differ. Among the Old World farmers, those dating from the Neolithic through the Late Bronze Age had higher complexity values than those from the Iron Age through the medieval period. The cluster analysis discerned foragers and farmers but also indicated similarity between hard food foragers and hard food farmers. Our findings reaffirm that DMTA is capable of distinguishing human diets. We found that foragers and farmers, in particular, differ in their microwear signatures across the globe. There are some exceptions, but nothing that would be unexpected given the range of human diets and food preparation techniques. This study indicates that in general DMTA is an efficacious means of paleodietary reconstruction in humans.

Surface Replication, Fidelity and Data Loss in Traditional Dental Microwear and Dental Microwear Texture Analysis

Dental microwear studies often analyze casts rather than original surfaces, although the information loss associated with reproduction is rarely considered. To investigate the sensitivity of high magnification (150x) microwear analysis to common surface replication materials and methods, we compared areal surface texture parameters (ISO 25178-2) and traditional microwear variables (pits and scratches) generated from teeth and casts of rat molars exposed to experimental diets involving hard and soft foods in which abrasive materials had been added. Although the data from the original and replicated surfaces were correlated, many significant differences were found between the resulting data of the casts and original teeth. Both areal surface texture parameters and traditional microwear variables showed diminished ability to discriminate between the eight diet treatments when casts were analyzed. When areal surface texture parameters and traditional microwear variables were combined into a single discriminant function analysis, the cast data and original data produced the most similar results. Microwear researchers tend to favor either texture analysis or traditional microwear methods, better results may be generated by combining them. Although surface textures were not accurately reproduced by the casts, they retained sufficient information to discriminate between microwear of the experimental diets to a degree similar to the original teeth.

Post-mortem alteration of diet-related enamel surface textures through artificial biostratinomy: A tumbling experiment using mammal teeth

In the fossil record, teeth are often all that remains of a fossil organism. Dental microwear texture analysis (DMTA) is a common proxy for diet using dental wear features at the μm-scale, enabling comparative and quantitative assessments of various feeding traits in extant and extinct species. In extinct species, original diet-related dental wear features may be overprinted by post-mortem alteration including fluvial transport. Here we experimentally investigate the effects of mechanical alteration on diet-related 3D enamel surface texture (3DST) patterns of different mammal teeth. Post canine teeth of Equus sp., Capreolus capreolus and Otomys sp. are tumbled in sediment-water suspensions using three different grain size fractions of sand. The 3DST of the enamel surfaces are measured prior to and after each tumbling interval and characterised using ISO normed surface texture and SSFA parameters. In all species, we find several parameters to be almost unaffected by tumbling (stable parameters), while other parameters show inconsistent-directional shifts (unstable parameters). For Otomys, all three sediment grain size fractions result in abrasion of peaks and a reduction of overall surface roughness. For Equus, tumbling results in visible abrasive changes in the original wear patterns and the introduction of new wear features. Capreolus capreolus shows high variability in surface texture patterns prior to and after the experiment, hence we see ambiguous trends for changes in parameter values. However, even after 336 h of tumbling the browsing C. capreolus can still be distinguished from the grazing Equus sp.Thus, biostratinomy may potentially modify diet-related 3DST causing non-systematic bias via mechanical abrasion, which is related to sediment grain size, duration of transport and geometry of teeth. However, the original diet-related 3DST is still preserved and a more prominent characteristic in DMT than the experimentally induced diagenetic alteration.