Patterns of molar variation in great apes and their implications for hominin taxonomy

Pilbrow, Varsha

doi:10.1007/978-1-4020-5845-5_2

Cited by 16 publications

(16 citation statements)

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“…This compares favorably with Pilbrow's species‐classification rates of 73–96% using 15 traditional measurements and with the results of Skinner et al based on scores on 8–12 principal shape components (Pilbrow,2006; Skinner et al,2009a). Our findings simultaneously support Pilbrow's (2006,2007) conclusion that hominid crown‐shape variation is an appropriate basis for taxonomic classification and underscore the potential of geometric dental analysis. That 100% accuracy is possible even with relatively small samples suggests these methods are well suited for paleontological analyses, where inadequate reference samples are common.…”

Section: Discussionsupporting

confidence: 86%

Allometric and Metameric Shape Variation in Pan Mandibular Molars: A Digital Morphometric Analysis

Singleton

Rosenberger

Robinson

et al. 2010

The Anatomical Record

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The predominance of molar teeth in fossil hominin assemblages makes the patterning of molar shape variation a topic of bioanthropological interest. Extant models are the principal basis for understanding dental variation in the fossil record. As the sister taxon to the hominin clade, Pan is one such model and the only widely accepted extant hominid model for both interspecific and intraspecific variation. To explore the contributions of allometric scaling and meristic variation to molar variation in Pan, we applied geometric shape analysis to 3D landmarks collected from virtual replicas of chimpanzee and bonobo mandibular molars. Multivariate statistical analysis and 3D visualization of metameric and allometric shape vectors were used to characterize shape differences and test the hypothesis that species of Pan share patterns of metameric variation and molar shape allometry. Procrustes-based shape variables were found to effectively characterize crown shape, sorting molars into species and tooth-row positions with !95% accuracy. Chimpanzees and bonobos share a common pattern of M 1 -M 2 metameric variation, which is defined by differences in the relative position of the metaconid, size of the hypoconulid, curvature of the buccal wall, and proportions of the basins and foveae. Allometric scaling of molar shape is homogeneous for M 1 and M 2 within species, but bonobo and chimpanzee allometric vectors are significantly different. Nevertheless, the common allometric shape trend explains most molar-shape differences between P. paniscus and P. troglodytes. When allometric effects are factored out, chimpanzee and bonobo molars are not morphometrically distinguishable. Implications for hominid taxonomy and dietary reconstruction are discussed. Anat Rec, 294:322-334, 2011. V V C 2010 Wiley-Liss, Inc.

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Section: Discussionsupporting

confidence: 86%

Allometric and Metameric Shape Variation in Pan Mandibular Molars: A Digital Morphometric Analysis

Singleton

Rosenberger

Robinson

et al. 2010

The Anatomical Record

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“…Tooth shape in particular has been found to be related to the mechanical properties of foods eaten (Lucas, 2004). Morphological differences can also be used to infer phylogenetic distance between taxa (Plavcan, 1993;Uchida, 1996;Plavcan and Cope, 2002;Scott and Lockwood, 2004;Pilbrow, 2007). Morphological differences can also be used to infer phylogenetic distance between taxa (Plavcan, 1993;Uchida, 1996;Plavcan and Cope, 2002;Scott and Lockwood, 2004;Pilbrow, 2007).…”

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confidence: 99%

“…In studying tooth shape, we may learn of broad dietary categories (Ungar, 2007a), but also about subtler distinctions, such as the role of fallback resources and the degree of niche separation among species (Rosenberger and Kinzey, 1976;Kinzey, 1978;Rosenberger, 1992;M'Kirera and Ungar, 2003;Ungar and M'Kirera, 2003;Ulhaas et al, 2004;Lambert et al, 2004;Ungar, 2004;Lambert, 2007). Thus, examination of dental characteristics in extant species may provide insights into the behavior, ecology, diversity, and evolution of extinct forms (Kay, 1975;Maier, 1984;Ungar and M'Kirera, 2003;Ungar, 2004;Pilbrow, 2007;Ungar, 2007a). Thus, examination of dental characteristics in extant species may provide insights into the behavior, ecology, diversity, and evolution of extinct forms (Kay, 1975;Maier, 1984;Ungar and M'Kirera, 2003;Ungar, 2004;Pilbrow, 2007;Ungar, 2007a).…”

mentioning

confidence: 99%

“…Morphological differences can also be used to infer phylogenetic distance between taxa (Plavcan, 1993;Uchida, 1996;Plavcan and Cope, 2002;Scott and Lockwood, 2004;Pilbrow, 2007). Thus, examination of dental characteristics in extant species may provide insights into the behavior, ecology, diversity, and evolution of extinct forms (Kay, 1975;Maier, 1984;Ungar and M'Kirera, 2003;Ungar, 2004;Pilbrow, 2007;Ungar, 2007a).…”

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A dental topographic analysis of chimpanzees

Klukkert

Teaford

Ungar

2012

American J Phys Anthropol

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Molar tooth morphology is generally said to reflect a compromise between phylogenetic and functional influences. Chimpanzee subspecies have been reported to exhibit differences in molar dimensions and nonmetric traits, but these have not been related to differences in their diets. And in fact, observations to date of the diets of chimpanzees have not revealed consistent differences among subspecies. This study uses dental topographic analyses shown to reflect diet-related differences in occlusal morphology among primate species, to assess within-species variation among chimpanzee subspecies. High-resolution casts from museum collections were examined by laser scanning, and resulting data were analyzed using GIS algorithms and a two-factor ANOVA model. Although differences were noted between wear stages within subspecies in surface slope, relief, and angularity, none were found to distinguish the subspecies from one another in these attributes. This might reflect limitations in the ability of this method to detect diet-related differences, but is also consistent with a lack of differences in functionally relevant aspects of occlusal morphology among chimpanzee subspecies.

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“…The size and shape of teeth are adapted to respond to the different functional demands required to break down foods with various phys-ical properties [Lucas, 1979;Luke and Lucas, 1983;Lucas and Luke, 1984;Dean and Benyon, 1991;Lucas and Teaford, 1994;Hillson, 2003;Pilbrow, 2007;Berthaume, 2016]. For example, primates that focus on a diet predominantly consisting of leaves are characterized by molars with high cusps, thin enamel and long shearing blades, while primates that rely on hard object foods tend to have posterior teeth with thicker enamel layers, low cusps and a generally flatter occlusal surface [Kay, 1978;Kay and Hylander, 1978;Strait, 1993;M'Kirera and Ungar, 2003;Ungar and M'Kirera, 2003;Berthaume, 2014].…”

Section: Introductionmentioning

confidence: 99%

Tooth Wear Inclination in Great Ape Molars

Knight-Sadler¹,

Fiorenza²

2017

IJFP

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Primate dietary diversity is reflected in their dental morphology, with differences in size and shape of teeth. In particular, the tooth wear angle can provide insight into a species' ability to break down certain foods. To examine dietary and masticatory information, digitized polygon models of dental casts provide a basis for quantitative analysis of wear associated with tooth attrition. In this study, we analyze and compare the wear patterns of Pongo pygmaeus, Gorilla gorillagorilla and Pan troglodytes schweinfurthii lower molars, focusing on the degree of inclination of specific wear facets. The variation in wear angles appears to be indicative of jaw movements and the specific stresses imposed on food during mastication, reflecting thus the ecology of these species. Orangutans exhibit flatter wear angles, more typical of a diet consisting of hard and brittle foods, while gorillas show a wear pattern with a high degree of inclination, reflecting thus their more leafy diet. Chimpanzees, on the other hand, show intermediate inclinations, a pattern that could be related to their highly variable diet. This method is demonstrated to be a powerful tool for better understanding the relationship between food, mastication and tooth wear processes in living primates, and can be potentially used to reconstruct the diet of fossil species.

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Patterns of molar variation in great apes and their implications for hominin taxonomy

Cited by 16 publications

References 70 publications

Allometric and Metameric Shape Variation in Pan Mandibular Molars: A Digital Morphometric Analysis

Allometric and Metameric Shape Variation in Pan Mandibular Molars: A Digital Morphometric Analysis

A dental topographic analysis of chimpanzees

Tooth Wear Inclination in Great Ape Molars

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