Tooth chipping patterns in Archaeolemur provide insight into diet and behavior

Abstract

Objectives: Archaeolemur is a recently extinct genus of lemur that is often compared to some Cercopithecidae, especially baboons. This is due in part to their derived dentition, with large anterior teeth and reduced bilophodont molars. Research involving comparative morphology, analysis of coprolites, isotopes, and enamel structure, have suggested Archaeolemur had an omnivorous diet involving mechanically challenging items. Yet, microwear analysis of posterior teeth does not necessarily support this conclusion. Materials and Methods:In this macroscopic study, dental chipping was recorded on permanent teeth of Archaeolemur from different localities (53 individuals; 447 permanent teeth; including both A. edwardsi and A. majori specimens). This study aimed to compare chipping patterns across the dentition of Archaeolemur with chipping in other primates. Results:The results show enamel chipping was prevalent on the anterior teeth of Archaeolemur (38.9% of anterior teeth showed at least one fracture) yet rare in posterior teeth (9%). There was a decrease in chipping frequency across the dentition, moving distally from incisors (50%; 20/40), through caniniform teeth (30%; 15/50), premolars (9.5%; 16/169), and molars (8.5%; 16/188).Discussion: The results support previous research suggesting Archaeolemur had a varied omnivorous diet in which the anterior dentition was used for extensive food processing. This likely included mechanically challenging items such as tough/hard large fruits, small vertebrates, and crustaceans. Such a high rate of chipping in the anterior dentition is uncommon in other primates, with exception of hominins.

Assessing tooth wear progression in primates: A longitudinal study using intraoral scanning technology

“…The prominent tissue loss observed on functional cusps supports their additional susceptibility to wear, although this study focused on moderately worn molars. Assessment of tissue loss progression in later stages of wear, including the examination of different types of dental tissue loss such as fractures, is warranted (Towle et al, 2021b; Towle et al, 2023). It is conceivable that the wear on non-functional cusps may intensify over time, consistent with alterations observed in the plane of occlusion over an individual’s lifespan.…”

“…Assessing wear progression will allow this to be directly assessed, not only in wild primates, but also in controlled laboratory settings using wear simulation machines. Such techniques can also be used to look at the association between tissue loss and other variables (e.g., microwear and underlying enamel microstructure; e.g., Hua et al, 2015; Towle et al, 2023). Variation in bite force across the dental arcade, and particularly during the eruption of permanent teeth, can influence wear dynamics over time, potentially reducing tooth wear on individual teeth as more tooth contacts are made (Lucas, 2004).…”

Tooth chipping patterns and dental caries suggest a soft fruit diet in early anthropoids

“…Extant anthropoids that regularly eat hard foods (e.g., sakis, mandrills, sooty mangabeys, and Raffles' banded langurs) show high overall chipping prevalence, with over 25% of teeth showing at least one chip, and some tooth types approaching 50% (Fannin et al, 2020; Towle, Constantino, et al, 2023; Towle & Loch, 2021). Species that consume hard foods as part of their diet but only at certain times of the year (e.g., brown woolly monkeys) have intermediate chipping frequencies of 15%–20%, and species in which hard foods do not make up a significant amount of the diet at any time of the year have the lowest chipping frequencies of under 10% (e.g., gibbons, chimpanzees, western red colobus, and Western lowland gorilla; Fannin et al, 2020; Towle & Loch, 2021).…”

“…In this study, we utilize frequencies of antemortem enamel chipping prevalence to evaluate the likelihood of habitual durophagy in Fayum anthropoids. Chipping is suggested to be a reliable indicator of hard object mastication, with hard object feeders showing high rates of chipping (Fannin et al, 2020; Towle et al, 2023a; Towle & Loch, 2021). Dental caries has been associated with soft fruit eating in extant anthropoids (Colyer, 1931; Lovell, 1990; Stoner, 1995; Towle et al, 2022) and therefore would be supportive of soft/sugary fruit consumption if found in association with low rates of tooth fractures in early anthropoids.…”

Dental caries in living and extinct strepsirrhines with insights into diet

“…Caries is not only a phenomenon observed in extant taxa but has also been observed in several extinct primate and other mammalian (see Selig & Silcox, 2021;Towle et al, 2024) and non-mammalian taxa (e.g., Kear, 2001). For example, Fuss et al (2018) described a carious molar of a Middle Miocene dryopithecine hominid dated to about 12.5 million years ago.…”