Variation in hominoid molar enamel thickness

Smith, Tanya M.; Olejniczak, Anthony J.; Martin, Lawrence; Reid, Donald J.

doi:10.1016/j.jhevol.2005.02.004

Cited by 97 publications

(102 citation statements)

References 30 publications

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“…This suggests that variation in molar size (and possibly body mass) may explain some of the developmental variation within this mixed sample. Further, the results for crown formation time trends in successive molars suggest that trends in tooth size may parallel trends in crown formation time [also see Smith et al (2005) for a related discussion on trends in enamel thickness in this sample].…”

Section: Variation In Incremental Developmentmentioning

confidence: 90%

“…Conover's (1999) recommended adaptation of the Jonckheeree Terpstra test for trends was used to test for a gradient in rate from inner to outer cuspal enamel. Spearman's rho is the statistic of choice for assessing the level of significance of the JonckheereeTerpstra test statistic, and it is a more appropriate test for trends than the parametric ANOVA model, which does not explicitly test for directional differences (discussed further in Smith et al, 2005).…”

Section: Data Collection and Analysismentioning

confidence: 99%

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Molar development in common chimpanzees (Pan troglodytes)

Smith

Reid

Dean

et al. 2007

Journal of Human Evolution

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Section: Variation In Incremental Developmentmentioning

confidence: 90%

Section: Data Collection and Analysismentioning

confidence: 99%

Molar development in common chimpanzees (Pan troglodytes)

Smith

Reid

Dean

et al. 2007

Journal of Human Evolution

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“…[25][26][27] Comparisons of dental enamel thickness between the two species also reveal highly overlapping ranges and statistically indistinguishable means. 28,29 This is somewhat surprising given differences in jaw morphology and the material properties of dietary items between the two species. 30, 31 Gantt 32 and Ho et al 4 noted that fossil orangutans show thick enamel, although this was not quantified in either study, nor were comparisons made among fossil groups.…”

Section: Introductionmentioning

confidence: 99%

“…5,24,36,37 Finally, these results are considered in light of recent studies of enamel thickness within fossil and extant Homo sapiens, 35,[38][39][40] which are known to show a similar pattern of dental reduction over the same period. Given the significance of enamel thickness in assessments of hominoid systematics 28,29,32,35,41 and dental functional morphology, 33,34,42,43 characterization of enamel thickness within a geographically and temporally diverse hominoid genus will also permit more refined comparisons of limited samples of other fossil apes and humans.…”

Section: Introductionmentioning

confidence: 99%

Dental tissue proportions in fossil orangutans from mainland Asia and Indonesia

Smith

Bacon²,

Demeter

et al. 2011

Hum Origins Res

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Orangutans (Pongo) are the only great ape genus with a substantial Pleistocene and Holocene fossil record, demonstrating a much larger geographic range than extant populations. In addition to having an extensive fossil record, Pongo shows several convergent morphological similarities with Homo, including a trend of dental reduction during the past million years. While studies have documented variation in dental tissue proportions among species of Homo, little is known about variation in enamel thickness within fossil orangutans. Here we assess dental tissue proportions, including conventional enamel thickness indices, in a large sample of fossil orangutan postcanine teeth from mainland Asia and Indonesia. We find few differences between regions, except for significantly lower average enamel thickness (AET) values in Indonesian mandibular first molars. Differences between fossil and extant orangutans are more marked, with fossil Pongo showing higher AET in most postcanine teeth. These differences are significant for maxillary and mandibular first molars. Fossil orangutans show higher AET than extant Pongo due to greater enamel cap areas, which exceed increases in enamel-dentine junction length (due to geometric scaling of areas and lengths for the AET index calculation). We also find greater dentine areas in fossil orangutans, but relative enamel thickness indices do not differ between fossil and extant taxa. When changes in dental tissue proportions between fossil and extant orangutans are compared with fossil and recent Homo sapiens, Pongo appears to show isometric reduction in enamel and dentine, while crown reduction in H. sapiens appears to be due to preferential loss of dentine. Disparate selective pressures or developmental constraints may underlie these patterns. Finally, the finding of moderately thick molar enamel in fossil orangutans may represent an additional convergent dental similarity with Homo erectus, complicating attempts to distinguish these taxa in mixed Asian faunas.

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“…Over the course of an organism's lifetime, mechanical wear on these resources must be minimized, while the net energy obtained from food, or in some cases invested in reproduction, is maximized. These physiological resources vary across organisms, including oystercatcher beaks [182], wasp ovipositors [79], the mandibles of plant-eating insects [158], and the molar enamel of mammals [177,114,167,143], including modern and extinct hominins [112,170,191].…”

Section: Introductionmentioning

confidence: 99%

Dedication. Acknowledgments

2011

The Acquisition of German

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xvii Dedication xixAcknowledgments xx . See panel C. for a scenario where one prey is preferred over another. C. A tri-trophic system, where a top-predator consumes a meso-predator, which in turn consumes two prey. The sizes of the nodes denote relative abundance, and the thickness of the arrows denote the magnitude of the biomass flow. The top-predator in the leftmost network is relatively abundant, depressing the meso-predator population, thereby limiting the meso-predator's e↵ect on the two prey populations. The two rightmost networks (boxed) have reduced top-predator populations. In both cases, the meso-predator has greater abundance due to decreased predation pressure. However, in one scenario, both prey are preferred equally, resulting in apparent competition dynamics. In the second scenario, one prey is preferred over another, resulting in an asymmetric cascade. Such preferences could result from specific anatomical constraints of the meso-predator, a scenario explored in Chapter 4. C 1 and C 2 , and 4 prey: r 1 r 4 ) is represented by both pairwise interaction distributions for each link, and a network-level interaction distribution for the system. Link thickness represents the median link-strength, shown with the vertical bar in each pairwise interaction distribution. B-C. Both model food-webs X and Y have link-strengths drawn from the NLID. In model food-web X, the weights are distributed similar to the median weights of the empirical web (i.e. equivalent structure), but they are distributed di↵erently among nodes (i.e. alternative interactions). In model Y , the weight structure is di↵erent than that of the empirical web (i.e. alternative structure), and necessarily, the distribution of weights among nodes di↵ers as well (i.e. alternative interactions). Dotted nodes indicate those with link-strengths that di↵er from the median link-strengths of the empirical food-web. D-F. Given a single niche axis based on a continuous resource trait (e.g. body size) where prey are ranked from r 1 to r 4 , distributions of resource use are shown for the two consumers. Representations of dietary overlap illustrate higher similarity in diet between predators of the empirical system and model X, whereas the consumers in model Y have little dietary overlap, despite sharing the same NLID. 5 A-C. Sensitivity analyses of the Saskatchewan, Amboseli, and Lake Naivasha food-web ensembles, respectively. Similarity values for each cuto↵ (s i ) for Model 2 are on the y-axis, and the x-axis ranges from a lower standard deviation (SD) than the empirical SD to a higher SD (such that the empirical SD is central to the range; stippled vertical line). The colored data points represent the median similarity indices for each cuto↵ value (legend), while the top and bottom whiskers denote the 25 th and 75 th percentiles, respectively. The underlined values mark the standard deviation corresponding to the highest average similarity across cuto↵ values. For all systems, the highest average similarity is close to or exactly matches ...

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Variation in hominoid molar enamel thickness

Cited by 97 publications

References 30 publications

Molar development in common chimpanzees (Pan troglodytes)

Molar development in common chimpanzees (Pan troglodytes)

Dental tissue proportions in fossil orangutans from mainland Asia and Indonesia

Dedication. Acknowledgments

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