SPSS lectures part 6 (in English)

Paleobiology, 2012

A developmental model, based upon murine rodents, has been proposed by to explain lower molar proportions in mammals. We produce a clade-wide macroevolutionary test of the model using the dental evolutionary trends in a unique radiation of extinct mammals endemic to South America (''Meridiungulata'') that comprise a diverse array of molar morphologies. All of the South American ungulate groups examined follow the inhibitory cascade model with the exception of two groups: Interatheriidae (Notoungulata) and Astrapotheria. For most taxa studied, ratios between lower molar areas are greater than 1.0, indicating a weak inhibition by m1 on the subsequent molars in the tooth row, and a trend to greater absolute size of the posterior molars. Comparisons of mean ratios between clades indicate that a significant phylogenetic signal can be detected, particularly between the two groups within Notoungulata-Typotheria and Toxodontia. Body mass estimates were found to be significantly correlated with both m3/m1 and m2/m1 ratios, suggesting that the larger body size achieved the weaker inhibition between the lower molars. Molar ratio patterns are examined and discussed in relation to the independent and numerous acquisitions of hypsodonty that are characteristic of dental evolution in ''Meridiungulata.''

The use of mesowear to infer diets of extinct species is fast becoming widespread in palaeoecological studies. Nevertheless, traditional mesowear analyses suffer from a specimen number limitation, in that a minimum number of specimens identified to the species level is necessary to make accurate dietary predictions. This is problematic in many fossil African antelope (Mammalia: Bovidae) assemblages, where isolated teeth cannot always be assigned to species. Hereweexplore the possibility of using simple dental metrics to predict diets on the basis of individual teeth as well as gnathic rows using linear discriminant function analyses.We find that browsers are accurately classified at both the individual and species levels, across all models and tooth positions. Mixed feeders and grazers are classified accurately only sometimes, and this is probably a reflection of the more limited sample size of larger bodied species in our study. Body size was a highly significant predictor of the i...

The occlusal morphology and continuous molar replacement in elephants provide a very effective functional area for grinding the biomass that is more or less abrasive. Parts of two subsequent molars contribute to the ''functional area of the dentition'' (FAD). The FAD size, measured in cm 2 , is associated with age and body size. The FAD stage is indicated by the specific teeth contributing to the FAD and represents the individual age. This study concentrates on Mammuthus primigenius and compares the FAD stages, as derived from growth series, with the fossil Elephas antiquus, as well as the extant Elephas maximus and Loxodonta africana. During the life history of the taxa studied, the functional area increases simultaneously with an increase in body size, but decreases severely in senile age stages. In some senile individuals, the FAD is only about 20-50 % of the mean area of an adult animal. The reduction of the FAD beyond a specific size does not mean an immediate starvation of the animal. The general constitution of the individual and the resources of fat accumulation earlier may support the animal for some time but certainly not over a longer period. Nevertheless, the highly reduced functional area was sufficient to keep the animal alive despite its full adult body mass. A much larger FAD in all adult stages provides the energy requirements needed for all additional life functions including competition and reproduction.

Morphological convergence amongst species inhabiting similar environments but having different evolutionary histories is a concept central to evolutionary biology. Cases of divergent evolution, where there is morphological divergence between closely related species exploiting different environments, are less well studied. Here we show divergent evolution in the morphology of the proximal phalanges of several closely related African antelope species inhabiting different environments. This morphological divergence was consistently observed in both a neutral morphospace and an externally ordinated morphospace. Divergence, but not convergence, was also observed when size and shape were considered independently. Finally, convergent evolution of the morphology of the proximal phalanges was observed, but only in the externally ordinated morphospace. Size shows less correlation with phylogeny than does shape. Therefore, we suggest that divergence in size will occur more readily when a species encounters new environmental conditions than divergence in shape. These findings are compatible with observations of rapid dwarfing on islands (Foster's rule).

Evolution, 2010

Mandibles and teeth of ungulates have been extensively studied to discern the functional significance of their design. Grazing ungulates have deeper mandibles, longer coronoid processes, flatter incisor arcades, and more hypsodont molars in comparison to browsers. If the functional significance of both mandible and teeth shapes is well-established, it remains uncertain to what extent mandible shapes are really adapted to grazing, meaning that they evolved either to serve their current biological function or just as a structural requirement to accommodate higher crowned molars. Here, we address this question by studying the contribution of phylogeny, hypsodonty, and body size to mandibular shape variation. The mandible shape appeared to be significantly influenced by hypsodonty but not by body size. Interestingly, hypsodonty-related changes influenced the tooth row in artiodactyls and perissodactyls significantly but in the opposite directions, which is ultimately related to their different digestive strategies. Yet, we obtained a strong phylogenetic effect in perissodactyls, suggesting that their mandible shape should be strongly inherited.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Summary 1. Habitat-related differences in size in a population of fallow deer (Dama dama L.) occupying the Blue Mountains, Otago, New Zealand, were identified by using five measurements from the mandibles of 1302 deer collected between 1983 and 1989. The measurements were standardized for age and sex, and discriminant analyses were used to compare mandible size between areas within the population's range. 2. Deer from areas containing mainly indigenous beech (Nothofagus) forest were significantly smaller than those from areas containing mainly exotic plantations, reflecting differences in the availability of preferred foods. 3. Adult deer killed between 1983 and 1989 were significantly larger than those killed in 1972-73, presumably reflecting habitat improvement resulting from a progressive reduction in deer density by hunting from 1960 to 1985. For deer less than 2 years old, however, the increase in size between the two periods was smaller (and not significant for females). 4. These results, coupled with information in diet and food sources, suggest the relationship between deer size and deer density in New Zealand forests is not linear. 5. Standardization for age and sex greatly simplified analysis of size differences. Diastema height was a more sensitive indicator of range-related differences in skeletal size than the more traditionally used total jaw length.

NEXUS: The Canadian Student Journal of Anthropology, 1982

This study assesses the utility of T-scores for discerning taxonomic categories in Plio-Pleistocene hominids by analysis of the dental metrics of the South African australopithecines. The hominids are divided into robust and gracile samples and Tscores and correlations between these samples are determined. Following a limited comparison of correlations between two non-human primate species the australopithecine T-scores and correlations are suggested to be close to the levels expected if the differences between samples were explained by sexual dimorphism. RESUME Cette etude etablit I' utilite des T-scores pour distinguer les categories taxonomiques des hominiens du Plio-Pleistocene par l'analyse des mesures dentaires des australopitheques Sud-Africains. Ces hominiens sont divises en deux sortes d' echantillons: robustes et graciles, et T-scores et correlations sont determines parmi ces echantillons. En se basant sur une comparaison limitee des correlations entre deux especes de primate non humains, les T-scores et les correlations a~stralopitheques semblant etre proches des niveaux surquels on pourrait s'attendre si les differences entre ces echantillons etaient expliquees par Ie dimorphisme sexuel.

American Journal of Physical Anthropology, 1973

Proceedings. Biological sciences / The Royal Society, 2012

We examine the relationship between mesowear variables and carbon and nitrogen isotopes in 16 species of African antelope (Mammalia: Bovidae). We show significant differences in carbon and nitrogen isotope values between individuals exhibiting sharp versus round cusps, and high versus low occlusal relief. We show significant correlations between mesowear variables and both carbon and nitrogen isotopes. We find significant correlations between mesowear score and nitrogen, but not carbon isotopes. Finally, we find no significant correlations between hypsodonty index and either isotope examined. Our results provide strong support for the use of mesowear variables in palaeodietary reconstructions of antelopes. Our results further suggest that for the antelopes examined here, mesowear signals are a direct result of diet, while hyposodonty may be the result of phylogenetic legacy.