Grit your teeth and chew your food: Implications of food material properties and abrasives for rates of dental microwear formation in laboratory Sapajus apella (Primates)

Dental microwear of Neogene cercopithecoids from the Turkana Basin, Kenya

Reconstructions of the diets of individual fossil species can help us better understand the adaptive radiations of higher-level primate taxa. Some researchers have posited that folivory was key to the divergence of cercopithecoids from the catarrhine stem, with bilophodonty reflecting an adaptation for leaf consumption. Others have questioned this model, suggesting that dental functional morphology and wear patterns are more consistent with frugivory and perhaps hard-object consumption. Here, we present new microwear texture data (n = 22) that might contribute to the discussion. Specimens were sampled from Buluk (∼17 Ma, Early Miocene, Noropithecus bulukensis) and Lothagam (∼8-4 Ma, Late Miocene to Early Pliocene, Parapapio lothagamensis/sp. indet and fossil Colobinae) in the Turkana Basin, Kenya, and compared with a select group of extant taxa. Point clouds were generated from high-resolution replicas of molar teeth using a white light confocal profiler and analyzed using scale-sensitive fractal analysis. Results of dental microwear texture analyses for both fossil samples align with those of extant grass (Theropithecus) and leaf (Trachypithecus) eaters and differ significantly from those of frugivores/generalists (Macaca, Papio) and hard-object specialists (Cercocebus). While both Noropithecus and Parapapio postdate the divergence of the cercopithecoid clade from other catarrhines, these results are largely consistent with previous work on the dietary ecology of the early papionin Parapapio from Lothagam and the traditional 'tough-food' model of leaves/grasses. Some previous Noropithecus dietary reconstructions indicated a diet of harder objects or fruits. Thus, the discrepancy between the microwear results and previous dietary reconstructions for N. bulukensis is unexpected. These results raise hypotheses that may help provide new context and insights into the radiation of this important superfamily of primates.

Dietary Variation Among Herculaneum's Victims of Mt. Vesuvius via Dental Microwear Texture Analysis

The Roman site of Herculaneum provides an extraordinary opportunity to reconstruct ancient diets in the context of life course theory because everyone died simultaneously due to the eruption of Mount Vesuvius in AD 79.

OBJECTIVES

The current study addresses three primary hypotheses: (1) Subadult diets changed as children aged, (2) adult diets differed from subadult diets, and (3) male and female diets differed as they age.

MATERIALS AND METHODS

This study includes dental microwear texture data from 58 adults (age 16+) and 23 subadults (age 0-16) recovered by Sarah Bisel from within and near to storage rooms adjacent to Herculaneum's beach. The adults include 27 females and 31 males. Dental microwear texture analysis (DMTA) employed standard procedures: data collection used a white-light confocal profiler at 100×. The DMTA variables were complexity, anisotropy, textural fill volume, and scale of maximum complexity. Statistical methods used Bayesian versions of analysis of variance and correlation (Bayes factors above 1.5 were considered meaningful and above 3.0 significant) as well as discriminant function analysis and binary logistic regression.

RESULTS

No differences emerged among the children. Adult diets were significantly lower than the subadults for anisotropy. Among the adults, age affected the females more, particularly for anisotropy.

DISCUSSION

Subadult diets did not vary by age, but they did vary. The lower adult anisotropy indicates each adult ate a greater variety of foods compared to the subadults. As females aged, however, their diets became more restricted compared to the males. Overall, age and sex affected the Herculaneum diet.

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

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

Dental topography of the Oligocene anthropoids Aegyptopithecus zeuxis and Apidium phiomense: Paleodietary insights from analysis of wear series

Fossil primate dietary inference is enhanced when ascertained through multiple, distinct proxies. Dental topography can be used to assess changes in occlusal morphology with macrowear, providing insight on tooth use and function across the lifespans of individuals. We measured convex Dirichlet normal energy-a dental topography metric reflecting occlusal sharpness of features such as cusps and crests-in macrowear series of the second mandibular molars of two African anthropoid taxa from ∼30 Ma (Aegyptopithecus zeuxis and Apidium phiomense). Wear was quantified via three proxies: occlusal dentine exposure, inverse relief index, and inverse occlusal relief. The same measurements were calculated on macrowear series of four extant platyrrhine taxa (Alouatta, Ateles, Plecturocebus, and Sapajus apella) to provide an analogical framework for dietary inference in the fossil taxa. We predicted that Ae. zeuxis and Ap. phiomense would show similar patterns in topographic change with wear to one another and to extant platyrrhine frugivores like Ateles and Plecturocebus. The fossil taxa have similar distributions of convex Dirichlet normal energy to one another, and high amounts of concave Dirichlet normal energy 'noise' in unworn molars-a pattern shared with extant hominids that may distort dietary interpretations. Inverse relief index was the most useful wear proxy for comparison among the taxa in this study which possess disparate enamel thicknesses. Contrary to expectations, Ae. zeuxis and Ap. phiomense both resemble S. apella in exhibiting an initial decline in convex Dirichlet normal energy followed by an increase at the latest stages of wear as measured by inverse relief index, lending support to previous suggestions that hard-object feeding played a role in their dietary ecology. Based on these results and previous analyses of molar shearing quotients, microwear, and enamel microstructure, we suggest that Ae. zeuxis had a pitheciine-like strategy of seed predation, whereas Ap. phiomense potentially consumed berry-like compound fruits with hard seeds.

Enamel chipping and its ecological correlates in African papionins: Implications for hominin feeding behavior

African papionins are classic paleoecological referents for fossil hominins. Enamel chips on the teeth of baboons and hominins are argued to represent responses to similar dietary habits; however, a comprehensive analysis of modern papionin chipping is lacking, leaving open the question of analog suitability. Here, we investigate patterns of antemortem enamel chipping across a diverse set of African papionin species occupying a range of ecological niches. We compare papionin chipping frequencies to estimates for Plio-Pleistocene hominins to address hypotheses of habitat and/or dietary similarities. Antemortem chips in seven African papionin species were scored on intact postcanine teeth (P3-M3) using established protocols. Chip size was scored on a tripartite scale. Papio hamadryas and Papio ursinus-two common paleoecological referents-display higher levels of chipping than Plio-Pleistocene hominin taxa (Australopithecus and Paranthropus) posited to have similar dietary habits. Papio populations occupying dry or highly seasonal habitats accumulate more large chips than Papio taxa occupying more mesic habitats, and terrestrial papionins chip their teeth more often than closely related taxa occupying arboreal niches. Chipping is present on the teeth of all Plio-Pleistocene hominins; however, chipping in baboons (P. ursinus and P. hamadryas) consistently exceeds most hominin taxa. Chipping frequencies on their own do not reliably sort taxa into major dietary groupings. We conclude that the large differences in chipping frequency may instead reflect habitat use and food processing idiosyncrasies. Less chipping in Plio-Pleistocene hominin teeth compared to modern Papio is more likely attributable to differences in dental morphology rather than diet.

Feeding ecology of the last European colobine monkey, Dolichopithecus ruscinensis

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