Dental use wear in extinct lemurs: Evidence of diet and niche differentiation

Department of Anthropology, University of Massachusetts, 240 Hicks Way, Amherst, MA 01003, USA.
Journal of Human Evolution (Impact Factor: 3.73). 10/2004; 47(3):145-69. DOI: 10.1016/j.jhevol.2004.06.003
Source: PubMed


A new technique for molar use-wear analysis is applied to samples of all 16 species of extinct lemurs with known dentitions, as well as to a large comparative sample of extant primates. This technique, which relies on the light refractive properties of wear pits and scratches as seen under a standard stereoscopic microscope, has shown itself to be effective in distinguishing the diets of ungulates and extant primates. We draw dietary inferences for each of the 16 extinct lemur species in our database. There is a strong phylogenetic signal, with the Palaeopropithecidae showing use-wear signatures similar to those of the Indriidae; extinct lemurids (Pachylemur spp.) showing striking similarities to extant lemurids (except Hapalemur spp.); and Megaladapis showing similarities to Lepilemur spp. Only the Archaeolemuridae have dietary signatures unlike those of any extant lemurs, with the partial exception of Daubentonia. We conclude that the Archaeolemuridae were hard-object feeders; the Palaeopropithecidae were seed predators, consuming a mixed diet of foliage and fruit to varying degrees; Pachylemur was a fruit-dominated mixed feeder, but not a seed predator; and all Megaladapis were leaf browsers. There is no molar use wear evidence that any of the extinct lemurs relied on terrestrial foods (C4 grasses, tubers, rhizomes). This has possible implications for the role of the disappearance of wooded habitats in the extinction of lemurs.

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    • "A commonly employed dietary classification scheme follows that of Hofmann and Stewart (1972), in which browsers (<10% grass consumption) are identified by a predominance of pits over scratches, grazers (>90% grass) show a predominance of scratches over pits, and intermediate or mixed feeders show intermediate numbers of scratches, with some species tending toward the browser or grazer ends of the microwear spectrum (Solounias and Semprebon, 2002). The number of scratches and pits has been used to classify species into dietary categories using two primary methods: bivariate plotting of average scratch against average pit counts for each taxon to create a 'trophic triangle' (Solounias and Semprebon, 2002; Semprebon et al., 2004; Godfrey et al., 2004) and combining microwear and morphological characteristics using multivariate data exploration (i.e. principal components analysis, discriminant function analysis) to partition species among dietary guilds that are defined a priori based on observations of extant species (e.g. "
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    ABSTRACT: Microwear, the quantification of microscopic scratches and pits on the occlusal surfaces of tooth enamel, is a commonly used as a paleodietary proxy. For ungulates (hoofed mammals), scratch-dominant microwear distinguishes modern grazers from browsers, presumably as a result of abrasion from grass phytoliths (biogenic silica). However, it is also likely that exogenous grit (i.e., soil, dust) is a contributing factor to these scratch-dominant patterns, which may reflect soil ingestion that varies with feeding height and/or environmental conditions (e.g., dust production in open and/or arid habitats). This study assesses the contribution of exogenous grit to tooth wear by measuring the effects of fine- and medium-grained silica sand on tooth enamel using a novel live animal tooth molding technique. This study therefore constitutes the first controlled feeding experiment using ungulates and the first in vivo experiments using abrasives of different sizes. Four sheep were fed three diet treatments: 1) a mixture of Garrison and Brome hay (control), 2) hay treated with fine-grained silica sand (180-250 µm), and 3) hay treated with medium-grained silica sand (250-425 µm). We found a significant increase in pit features that was correlated with an increase in grain size of grit, corroborating earlier chewing simulation experiments that produced pits through grit-induced abrasion (i.e., the 'grit effect'). Our results support an interpretation of large silica grains fracturing to create smaller, more abundant angular particles capable of abrasion, with jaw movement defining feature shape (i.e., scratch or pit). © 2015. Published by The Company of Biologists Ltd.
    Full-text · Article · Apr 2015 · Journal of Experimental Biology
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    • "L'observation de la micro-usure peut être réalisée, en fonction de l'objet d'étude et de la problématique, avec un microscope électronique à balayage, un microscope confocal, ou une loupe binoculaire (stéréomicroscope). méthode a été appliquée avec succès chez les ongulés [18] [34] [44] [45] [46], les carnivores [47] [48] et les primates [13] [49]. "

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    • "manent upper incisors and the presence of an expanded articular facet on the posterior face of the mandibular condyle ( Tattersall and Schwartz , 1974 ; Wall , 1997 ) . Lepilemur diets seasonally comprise up to 100% leaves ( Thalmann , 2001 ) , and microwear patterns on Megaladapis molars also suggest extensive folivory ( Rafferty et al . , 2002 ; Godfrey et al . , 2004 ; Scott et al . , 2009 ) . Therefore , rather than reflecting shared ancestry , these phenotypes likely signify convergent evolution to highly folivorous diets and a leaf - cropping foraging method in separate clades descended from ancestors with already - reduced upper incisors ."
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    ABSTRACT: Humans first arrived on Madagascar only a few thousand years ago. Subsequent habitat destruction and hunting activities have had significant impacts on the island's biodiversity, including the extinction of megafauna. For example, we know of 17 recently extinct ‘subfossil’ lemur species, all of which were substantially larger (body mass ∼11–160 kg) than any living population of the ∼100 extant lemur species (largest body mass ∼6.8 kg). We used ancient DNA and genomic methods to study subfossil lemur extinction biology and update our understanding of extant lemur conservation risk factors by i) reconstructing a comprehensive phylogeny of extinct and extant lemurs, and ii) testing whether low genetic diversity is associated with body size and extinction risk. We recovered complete or near-complete mitochondrial genomes from five subfossil lemur taxa, and generated sequence data from population samples of two extinct and eight extant lemur species. Phylogenetic comparisons resolved prior taxonomic uncertainties and confirmed that the extinct subfossil species did not comprise a single clade. Genetic diversity estimates for the two sampled extinct species were relatively low, suggesting small historical population sizes. Low genetic diversity and small population sizes are both risk factors that would have rendered giant lemurs especially susceptible to extinction. Surprisingly, among the extant lemurs, we did not observe a relationship between body size and genetic diversity. The decoupling of these variables suggests that risk factors other than body size may have as much or more meaning for establishing future lemur conservation priorities.
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