Dental microwear texture analysis of two families of subfossil lemurs from Madagascar

Environmental Dynamics Doctoral Program, University of Arkansas, 113 Ozark Hall, Fayetteville, AR 72701, USA.
Journal of Human Evolution (Impact Factor: 3.73). 04/2009; 56(4):405-16. DOI: 10.1016/j.jhevol.2008.11.003
Source: PubMed


This study employs dental microwear texture analysis to reconstruct the diets of two families of subfossil lemurs from Madagascar, the archaeolemurids and megaladapids. This technique is based on three-dimensional surface measurements utilizing a white-light confocal profiler and scale-sensitive fractal analysis. Data were recorded for six texture variables previously used successfully to distinguish between living primates with known dietary differences. Statistical analyses revealed that the archaeolemurids and megaladapids have overlapping microwear texture signatures, suggesting that the two families occasionally depended on resources with similar mechanical properties. Even so, moderate variation in most attributes is evident, and results suggest potential differences in the foods consumed by the two families. The microwear pattern for the megaladapids indicates a preference for tougher foods, such as many leaves, while that of the archaeolemurids is consistent with the consumption of harder foods. The results also indicate some intraspecific differences among taxa within each family. This evidence suggests that the archaeolemurids and megaladapids, like many living primates, likely consumed a variety of food types.

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    • "[50] [52] [53]. "

    Full-text · Chapter · Apr 2015
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    • " 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.
    Full-text · Article · Dec 2014 · Journal of Human Evolution
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    • "Diet was entered into the analysis as a covariate using a set of binary-coded dummy variables representing the categorical folivore-frugivore-insectivore trichotomy used by Vinyard and Hanna (2005). The assignments of species to these three categories were taken from the foregoing study, with a single exception: the subfossil lemur Hadropithecus stenognathus was classified as a frugivore for this analysis rather than as a folivore based on recent studies of dental wear suggesting that this species is a hardobject feeder, like other archaeolemurids (Rafferty et al., 2002; Godfrey et al., 2004, 2005; Scott et al., 2009). However, this classification is also problematic. "
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    ABSTRACT: Among the Strepsirrhini, molar size does not exhibit a consistent dietary signal when body mass is used to size-adjust molar dimensions. This observation is also true for anthropoid primates, but when postcanine size is expressed relative to the size of the facial skeleton in this clade, folivorous anthropoids tend to have relatively larger postcanine teeth than anthropoids in other dietary categories. The contrast in the results generated by these two independent size variables appears to be related to systematic differences in facial size in the Anthropoidea, particularly between short-faced colobines and long-faced cercopithecines. The goal of this study was to determine whether a similar pattern of relationships characterizes strepsirrhines. Data on molar area, facial size, body mass, and diet for forty-three extant strepsirrhines and seven subfossil lemurs were analyzed using phylogenetic generalized least squares. Results indicate that strepsirrhine folivores tend to have larger molars than frugivores relative to the size of the facial skeleton. Insectivorous species exhibit a wide range of variation in relative molar size that appears to be taxonomically patterned: lorisids in this dietary category resemble folivores, whereas galagids resemble frugivores. These results confirm the generality of the anthropoid pattern and support the idea that, in some contexts, it may be useful to consider elements of the masticatory system relative to their functional and developmental environments rather than to overall organismal size. The biological significance of having large postcanine teeth relative to the size of the face, but not body mass, is discussed with reference to a model that identifies the size of the oral cavity as the most functionally relevant standard for assessing the relative size of the postcanine dentition.
    Full-text · Article · Oct 2012 · Journal of Human Evolution
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