Devonian ctenacanth chondrichthyans reached body sizes similar to modern great white sharks and therefore might have been apex predators of the Devonian seas. However, very little is known about the diet and feeding behaviours of these large ancestral sharks. To reconstruct their ecological properties, teeth of the large Famennian (Late Devonian) chondrichthyan Ctenacanthus concinnus from the Anti-Atlas, Morocco, were analysed. The teeth show strong tooth wear with deep horizontal as well as vertical scratches. Dental microwear texture analysis, a well-established method for the reconstruction of diet and commonly used in terrestrial vertebrates, was applied for the first time, to our knowledge, to Palaeozoic vertebrates in this study. Furthermore, finite element analysis was performed to test the biomechanical properties of the teeth. By combining both analyses, as well as palaeoenvironmental data and tooth morphology, we demonstrate that the results from only one method can be insufficient and misleading. Ctenacanthus concinnus most likely was an opportunistic feeder like many modern sharks. Direct evidence and the results of our analyses suggest that Ctenacanthus fed on ectocochleate cephalopods, other chondrichthyans and further vertebrates using a combination of head movements including lateral head shaking to cut large prey items.

Most faunas from the Mesozoic era were dominated by sauropod dinosaurs, the largest terrestrial animals to ever exist. These megaherbivores were remarkably diverse and widely distributed. Here we study three Late Jurassic faunas from the USA, Portugal and Tanzania, each approximately 150 million years old, which are known for their extreme sauropod diversity. Whereas general taxonomic composition was similar in these three faunas, the major clades differed in relative abundance. Moreover, their depositional strata record distinct climatic regimes. Using dental microwear texture analysis, we investigated the impact of these climate regimes and the resulting food availability on the different sauropod taxa. Wear patterns in camarasaurid macronarians show minimal variation across different climate regimes, supporting previous studies suggesting that these animals migrated to follow their preferred climate niche and food source. North American camarasaurids show similar wear patterns to those of Portuguese turiasaurs, another broad-crowned taxon, which did not exist in the Jurassic of North America. By contrast, where camarasaurids and turiasaurs co-occurred in Portugal, their microwear patterns are distinct, suggesting niche differentiation to avoid ecological competition between these two clades. Flagellicaudatan diplodocoids display highly variable wear patterns, indicating limited migration (and therefore seasonal variation in diet), which aligns with observed biogeography patterns in the USA. Early-branching titanosauriforms show highly distinct wear patterns between different climate regimes, which can probably be attributed to different abrasive loads in the respective habitats. Our results demonstrate that dental microwear texture analysis not only records dietary preferences but also reveals behaviour such as competition and migration related to dietary niches in past ecosystems.

Extant giant pandas are among the most herbivorous forms of the order Carnivora, feeding mainly on hard plant material. The first steps of their evolutionary lineage are of particular interest for our understanding of the factors that led to this specialized niche. The present work deals with newly discovered dental material of the primitive ailuropodine bear Kretzoiarctos beatrix from the Late Miocene locality of Hammerschmiede (Germany). This is the first report of the genus Kretzoiarctos outside the Iberian Peninsula, expanding its spatial range to Central Europe. All of the currently known localities with K. beatrix, from both Spain and Germany, are very similar in age (c. 11.9-11.4 Ma). The present material has distinct features that enable its taxonomic discrimination from other Miocene ursids of Europe, such as Ballusia, Ursavus, Miomaci, Agriarctos and Indarctos. A thorough comparison is conducted of all of these forms. The new specimens were used in a dental microwear texture analysis in combination with ecomorphological comparisons, to investigate the dietary habits of this primitive ailuropodine. The results suggest that Kretzoiarctos was not an eater of tough plant material like the extant giant panda but was more similar to the extant Tremarctos, exhibiting opportunistic behaviour with occasional consumption of meat.

Ingesta leaves distinct patterns on mammalian teeth during mastication. However, an unresolved challenge is how to include intraspecific variability into dietary reconstruction and the biomechanical aspects of chewing. Two extant populations of the grey wolf ( Canis lupus ), one from Alaska and one from Sweden, were analysed with consideration to intraspecific dietary variability related to prey size depending on geographical origin, sex and individual age as well as tooth function. Occlusal enamel facets of the upper fourth premolars, first molars and the second lower molar were analysed via three-dimensional surface texture analysis. The Swedish wolves displayed facets characterized by higher peaks and deeper, more voluminous dales, featuring an overall rougher surface than the wolves from Alaska. Compared to females, the Swedish male wolves had a slightly larger dale area and hill volume on their facets. Upper fourth premolars are smoother and had higher values in texture direction compared to upper first molars. The upper first molars were rougher than the occluding lower second molars and were characterized by larger and deeper dales. We find evidence supporting intraspecific dietary segregation, and antagonistic asymmetry in occlusal wear signatures. The data offer new insights into the roles of apex predators like the grey wolf.

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

Dental microwear texture (DMT) analysis is used to differentiate abrasive dental wear patterns in many species fed different diets. Because DMT parameters all describe the same surface, they are expected to correlate with each other distinctively. Here, we explore the data range of, and correlations between, DMT parameters to increase the understanding of how this group of proxies records wear within and across species. The analysis was based on subsets of previously published DMT analyses in guinea pigs, sheep, and rabbits fed either a natural whole plant diet (lucerne, grass, bamboo) or pelleted diets with or without added quartz abrasives (guinea pigs and rabbits: up to 45 days, sheep: 17 months). The normalized DMT parameter range (P4: 0.69 ± 0.25; M2: 0.83 ± 0.16) and correlation coefficients (P4: 0.50 ± 0.31; M2: 0.63 ± 0.31) increased along the tooth row in guinea pigs, suggesting that strong correlations may be partially explained by data range. A comparison between sheep and guinea pigs revealed a higher DMT data range in sheep (0.93 ± 0.16; guinea pigs: 0.47 ± 0.29), but this did not translate into more substantial correlation coefficients (sheep: 0.35 ± 0.28; guinea pigs: 0.55 ± 0.32). Adding rabbits to an interspecies comparison of low abrasive dental wear (pelleted lucerne diet), the softer enamel of the hypselodont species showed a smaller data range for DMT parameters (guinea pigs 0.49 ± 0.32, rabbit 0.19 ± 0.18, sheep 0.78 ± 0.22) but again slightly higher correlations coefficients compared to the hypsodont teeth (guinea pigs 0.55 ± 0.31, rabbits 0.56 ± 0.30, sheep 0.42 ± 0.27). The findings suggest that the softer enamel of fast-replaced ever-growing hypselodont cheek teeth shows a greater inherent wear trace consistency, whereas the harder enamel of permanent and non-replaced enamel of hypsodont ruminant teeth records less coherent wear patterns. Because consistent diets were used across taxa, this effect cannot be ascribed to the random overwriting of individual wear traces on the more durable hypsodont teeth. This matches literature reports on reduced DMT pattern consistency on harder materials; possibly, individual wear events become more random in nature on harder material. Given the species-specific differences in enamel characteristics, the findings suggest a certain species-specificity of DMT patterns.

Theropods were the dominating apex predators in most Jurassic and Cretaceous terrestrial ecosystems. Their feeding ecology has always been of great interest, and new computational methods have yielded more detailed reconstructions of differences in theropod feeding behaviour. Many approaches, however, rely on well‐preserved skulls. Dental microwear texture (DMT) analysis is potentially applicable to isolated teeth, and here employed for the first time to investigate dietary ecology of theropods. In particular, we test whether tyrannosaurids show DMT associated with more hard‐object feeding than compared to Allosaurus ; this would be a sign for higher levels of osteophagy, as has often been suggested. We find no significant difference in complexity and roughness of enamel surfaces between Allosaurus and tyrannosaurids, which conflicts with inferences of more frequent osteophagic behaviour in Tyrannosaurus as compared to other theropods. Orientation of wear features reveals a more pronounced bi‐directional puncture‐and‐pull feeding mode in Allosaurus than in tyrannosaurids. Our results further indicate ontogenetic niche shift in theropods and crocodylians, based on significantly larger height parameters in juvenile theropods which might indicate frequent scavenging, resulting in more bone–tooth contact during feeding. Overall, DMT is found to be very similar between theropods and extant large, broad‐snouted crocodylians and shows great similarity in feeding ecology of theropod apex predators throughout the Jurassic and Cretaceous.

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

This chapter is a comprehensive overview about the development in the field of quantitative wear analysis during the last 20 years. It focuses on specific interdisciplinary approaches that either introduced new viewpoints or solved technical problems, and in particular guided our projects within the DFG research unit 771 at the University of Hamburg. The scope of our group’s interest facilitates the historical shift from qualitative to quantitative wear analysis. Our research was driven by the urge to gain a deeper understanding of wear, which is much more than just traces, and develop a holistic view of the wear process on diverse materials. We start with a condensed historical review of selected developments, focus on the major debates that have influenced our understanding of tooth wear as a part of oral food processing, and set the context of our work within the larger theoretical framework. We show examples that the field of dental wear analyses is evolving on all scales, and that we are only beginning to comprehend the complex dental wear process as one factor amongst many driving evolution through dental adaptation. In particular, the combined studies based on museum material, in vivo, and in vitro experiments have shed new light on the importance of abrasives in the wear process, but also raised new questions for future research. A brief history of quantitative wear analyses with an appeal for a holistic view on dental wear processes

The bicolored shrew Crocidura leucodon so far has not been reported in Hamburg with certainty. Some plausible historical records before 1920 are present; in turn, two more recent records are doubtful for different reasons. Hence, the Red List status of the species for Hamburg has to be considered uncertain (either not present, or extinct). A citizen scientist provided a specimen of an unknown shrew, an accidental catch by a snap trap, to the Centrum für Naturkunde. The specimen was caught on the 12th of September 2019 in Tatenberg, Hamburg. It was morphologically and genetically clearly determined as C. leucodon. This find represents the first confirmed record of C. leucodon for the federal state of Hamburg and increases the number of shrew species recorded in Hamburg to five. The Red List status of the species will have to be reevaluated.

Teeth of vertebrates are under constant use and therefore show wear-induced traces on the surface. According to Williams (2005), the mechanism by which wear occurs is a mechanical and/or chemical process resulting in material loss. Wear facets, the smooth and polished contact areas between opposing teeth, form during force-fit chewing activity between antagonists due to attritional (tooth-tooth) and abrasional (tooth-substrate-tooth) contacts involving either some kind of resistant alimentary bolus or some other dental behavior with an empty mouth cavity (Maier & Schneck 1981). In mammals, the occlusion of dental surfaces produces characteristic facet patterns on the crown’s surface. Orientation and inclination of a facet are determined by tooth morphology, while the texture of the surface (e. g., complexity and roughness) is the result of the food ingested (e. g., Schulz et al. 2010, Winkler et al. 2019, Schulz-Kornas et al. 2020, this volume). Complementary patterns of wear facets on the occlusal surface of opposing teeth change in shape and size during ontogeny and therefore can be used for age determination (e. g., Baumann 1949, Grau et al. 1970, Habermehl 1985, Anders et al. 2011a,b, Ruf et al. 2020, this volume). Wear facet patterns begin to form as soon as the tooth crown erupts and antagonists occlude. Fortelius (1985) differentiated between primary and secondary occlusal surfaces. Facets on primary surfaces develop gradually on the enamel cover (i. e., enamel facets) and only later expose the dentin with increasing wear due to age. In those cases, the exposed dentin has no explicit function. Facets on a secondary surface are composed of enamel and dentin. Dentin exposure happens relatively fast and it forms depressions in close proximity to protruding enamel, and the combination of both has a specific function. Those facets remain constant for a relatively long period of time in the life of an animal (i. e., dentin facets interrupted and/ or surrounded by enamel bands). Facets on secondary surfaces are specialized occlusal surfaces that are mostly developed in herbivorous taxa with a horizontal power stroke movement, regardless of the direction (Koenigswald 2020, this volume). In these specialized cases enamel and exposed dentin function as a unit, and neighboring facets merge and may cover large areas composed of both tissues (e. g., occlusal surface of elephant molars). In correspondence, some mammal groups developed specialized dentitions (e. g., hypsodonty, euhypsodonty, A new wear facet terminology for mammalian dentitions

Mammalian teeth have to sustain repetitive and high chewing loads without failure. Key to this capability is the periodontal ligament (PDL), a connective tissue containing a collagenous fibre network which connects the tooth roots to the alveolar bone socket and which allows the teeth to move when loaded. It has been suggested that rodent molars under load experience a screw-like downward motion but it remains unclear whether this movement also occurs in primates. Here we use synchroton micro-computed tomography paired with an axial loading setup to investigate the form-function relationship between tooth movement and the morphology of the PDL space in a non-human primate, the mouse lemur (Microcebus murinus). The loading behavior of both mandibular and maxillary molars showed a three-dimensional movement with translational and rotational components, which pushes the tooth into the alveolar socket. Moreover, we found a non-uniform PDL thickness distribution and a gradual increase in volumetric proportion of the periodontal vasculature from cervical to apical. Our results suggest that the PDL morphology may optimize the three-dimensional tooth movement to avoid high stresses under loading.

Marine mammals are increasingly threatened in their habitat by various anthropogenic impacts. This is particularly evident in prey abundance. Understanding the dietary strategies of marine mammal populations can help predict implications for their future health status and is essential for their conservation. In this study we provide a striking example of a new dietary proxy in pinnipeds to document marine mammal diets using a dental record. In this novel approach, we used a combination of 49 parameters to establish a dental microwear texture (DMTA) as a dietary proxy of feeding behaviour in harbour seals. This method is an established approach to assess diets in terrestrial mammals, but has not yet been applied to pinnipeds. Our aim was to establish a protocol, opening DMTA to pinnipeds by investigating inter- and intra-individual variations. We analysed the 244 upper teeth of 78 Atlantic harbour seals ( Phoca vitulina vitulina ). The specimens were collected in 1988 along the North Sea coast (Wadden Sea, Germany) and are curated by the Zoological Institute of Kiel University, Germany. An increasing surface texture roughness from frontal to distal teeth was found and related to different prey processing biomechanics. Ten and five year old individuals were similar in their texture roughness, whereas males and females were similar to each other with the exception of their frontal dentition. Fall and summer specimens also featured no difference in texture roughness. We established the second to fourth postcanine teeth as reference tooth positions, as those were unaffected by age, sex, season, or intra-individual variation. In summary, applying indirect dietary proxies, such as DMTA, will allow reconstructing dietary traits of pinnipeds using existing skeletal collection material. Combining DMTA with time series analyses is a very promising approach to track health status in pinniped populations over the last decades. This approach opens new research avenues and could help detect dietary shifts in marine environments in the past and the future.

Dietary reconstruction in vertebrates often relies on dental wear-based proxies. Although these proxies are widely applied, the contributions of physical and mechanical processes leading to meso- and microwear are still unclear. We tested their correlation using sheep ( Ovis aries , n = 39) fed diets of varying abrasiveness for 17 months as a model. Volumetric crown tissue loss, mesowear change and dental microwear texture analysis (DMTA) were all applied to the same teeth. We hereby correlate: (i) 46 DMTA parameters with each other, for the maxillary molars (M1, M2, M3), and the second mandibular molar (m2); (ii) 10 mesowear variables to each other and to DMTA for M1, M2, M3 and m2; and (iii) volumetric crown tissue loss to mesowear and DMTA for M2. As expected, many DMTA parameters correlated strongly with each other, supporting the application of reduced parameter sets in future studies. Correlation results showed only few DMTA parameters correlated with volumetric tissue change and even less so with mesowear variables, with no correlation between mesowear and volumetric tissue change. These findings caution against interpreting DMTA and mesowear patterns in terms of actual tissue removal until these dental wear processes can be better understood at microscopic and macroscopic levels.

Dental microwear texture analysis (DMTA) is widely used for diet inferences in extant and extinct vertebrates. Often, a reference tooth position is analysed in extant specimens, while isolated teeth are lumped together in fossil datasets. It is therefore important to test whether dentalmicrowear texture (DMT) is tooth position specific and, if so, what causes the differences in wear. Here, we present results from controlled feeding experiments with 72 guinea pigs, which received either fresh or dried natural plant diets of different phytolith content (lucerne, grass, bamboo) or pelleted diets with and without mineral abrasives (frequently encountered by herbivorous mammals in natural habitats). We tested for gradients in dentalmicrowear texture along the upper cheek tooth row. Regardless of abrasive content, guinea pigs on pelleted diets displayed an increase in surface roughness along the tooth row, indicating that posterior tooth positions experience more wear compared with anterior teeth. Guinea pigs feedings on plants of low phytolith content and low abrasiveness (fresh and dry lucerne, fresh grass) showed almost no DMT differences between tooth positions, while individuals feeding on more abrasive plants (dry grass, fresh and dry bamboo) showed a gradient of decreasing surface roughness along the tooth row. We suggest that plant feeding involves continuous intake and comminution by grinding, resulting in posterior tooth positions mainly processing food already partly comminuted and moistened. Pelleted diets require crushing, which exerts higher loads, especially on posterior tooth positions, where bite forces are highest. These differences in chewing behaviour result in opposing wear gradients for plant versus pelleted diets.

Dental microwear texture analysis (DMTA) is a common wear proxy using dental wear features to reconstruct diet in extant and extinct taxa. Dietary reconstructions of extinct species can be biased due to post-mortem mechanical modification of the dental surface. These post-mortem surface alterations can be caused by material loss after death, or as the result of burial, excavation, or preparation processes. In this study, we explore postmortem surface alterations that occur during excavation, preparation, and conservation processes. We present a first general overview of unsuitable and suspicious dental surface scans and describe them both qualitatively and quantitatively using dental microwear texture (DMT) parameters. Finally, we compare these taphonomically altered surfaces to dental surfaces formed only by contact with a natural, ingested diet. We show that non-ingesta-related surfaces vary widely in morphologies. While some altered surfaces such as large post-mortem scratches or cracks in the enamel are easy to distinguish from ante-mortem ingesta-related wear features, others, such as remaining varnish covering the dental surface, are more obscure. The compiled surface defects dataset reveals that post-mortem altered surfaces often overlap with the parameter space of ingesta-related dental surfaces, but usually also include outliers with extreme values. To best identify dental surfaces with strong post-mortem alteration, we suggest using quantitative thresholds for frequently used DMT parameters for ingesta-related enamel surfaces based on literature values. However, with sufficient training and a reference database, these altered surfaces are detectable by an experienced user. Here we have compiled a first visual database of non-ingesta-related dental wear to help DMTA users identify these features and improve future DMTA studies.

SignificanceDental wear analyses are used for diet reconstruction in (paleo-)biology and (paleo-)anthropology. Whether microscopic traces (microwear) are primarily caused by internal (phytoliths) or external (mineral dust/grit) abrasives is still debated. We fed guinea pigs pelleted diets including mineral abrasives of different mineralogy, size, and amount to assess if resulting microwear differs from that caused by plant diets free of adhering abrasives. Sand-sized quartz and volcanic ash lead to extreme wear exceeding that caused even by phytolith-rich plants. Fine silt-sized quartz has a polishing effect, while clay-sized or larger silt-sized abrasives have no discernible effect. Thus, mineral dust ingestion is not unambiguously identifiable, whereas sand-sized grit causes characteristic microwear, allowing more detailed reconstruction of diet quality (mineral load) and environmental settings.

Saliva is an outstanding fluid, especially in terms of research and diagnostic possibilities. Its composition – namely electrolytes, hormones and especially its proteome – contains valuable information about feeding status, nutritional requirements as well as adaptation to diet and environment. The biggest advantage of saliva as a ’research tool’, however, is the possibility to collect it on a non-invasive basis; and there is almost no need for special training. Therefore, the results of our analysis of salivary proteomes from five different herbivorous species (camel, cattle, gelada baboon, goat, hamadryas baboon) already ignited major interest in salivary research, with the future goal to maintain and improve livestock productivity on one hand and certainly zoo animal welfare on the other. Moreover, the comprehensive analysis and identification of salivary proteins is a necessary pre-requisite to better understand animal physiology and diet adaptation.