Atypical indices in human paleontology

For a normally distributed variable, the index of atypicality associated with a measurement of that variable is defined as the probability of finding a result closer to the mean of the reference population than the one actually observed. The method extends straight forwardly to multivariate situations, thus providing a joint interpretation of multiple observations recorded on the same subject. In human palaeontology, atypicality indices allow to analyze and to compare the results obtained from variables closely associated with specific traits of the morphology. We briefly outline the principle of the method and give a computer program to carry out the calculations. Finally, we apply the use of univariate and multivariate atypicality indices to data recorded on 53 Upper Palaeolithic skulls.     

The morphofunctional approach in paleontology

The principle of actualism is regarded as the major principle in morphofunctional studies of fossil organisms, which is based on comparisons of evolutionary series of both extinct and extant taxa. The objects and specificity of morphofunctional studies in paleontology are discussed. The revelation of relationships between morphological and functional archetypes are considered to be the major task of these studies. The ecosystem approach, constrains on actualistic reconstruction imposed by various morphofunctional modi, hierarchy of functions at different levels of structural organization and at different phylogenetic stages are considered. It is shown that parallel development and the mosaic pattern of characters are accounted for by general morphogenetic mechanisms and heterochronies.     

Neurobiological approaches in vertebrate paleontology

The study of the central nervous system in extinct vertebrates is discussed. Historical development of the nervous system is restricted to a few morphological patterns. The foundation of structural conservatism of the nervous system is provided by the multifunctional character of any adaptive changes in the brain of vertebrates. The functional structural features allow the use of the nervous system for the resolution of some difficult questions of vertebrate evolution.     

Graphic normality test in human paleontology

In human palaeontology, samples are generally collections of objects gathered according to morphological criteria and their statistical analysis usually calls for caution because of the relatively small number of objects. Testing normality for such samples is a critical problem. The procedure suggested by Filliben, however, is particularly suitable for small to moderate sample sizes. Moreover, it provides a graphical presentation of the data that permits to locate each object within the distribution range. We briefly review the principle of the method and give a computer program to carry out the necessary computations and plot. Finally, we illustrate the method by studying the distribution of the maximum length and the maximum breadth for a sample of skulls of the Upper Palaeolithic.     

Relative index of inequality: definition, estimation, and inference

The relative index of inequality (RII) is a commonly used measure of the extent to which the occurrence of an outcome such as chronic illness or early death varies with socioeconomic status or some other background variable. The standard RII estimator applies only to linear variation in incidence rates. In this paper a general definition of the RII is introduced, alternative approaches to point estimation are considered, and a parametric bootstrap method is suggested for the construction of approximate confidence intervals. Estimation based on cubic splines fitted by maximum penalized likelihood is developed in some detail, and the proposed approach handles naturally the commonly needed adjustment for a 'standardizing' covariate such as age. Death rates in a large longitudinal study in England and Wales from 1996-2000 are analyzed in order to illustrate the various methods. A small simulation study explores the relative merits of different estimators. The approach based on cubic splines is found to reduce bias substantially, at the expense of some increase in variance, when variation in incidence rates is nonlinear.     

The Hawaiian Menehune in myth and paleontology

The paleontological evidence forHomo floriensis on the island of Flores in Indonesia provides evidence for a small-bodied hominin proportionately equivalent to a Jamaican child of the current era. Evidence is presented that these hominins coexisted withHomo sapiens for some millennia on the island of Flores. The extensive mythology of the Hawaiian Menehune, or little people, may have its origin traced to this early coexistence on the island of Flores. Hominins such asHomo floriensis may represent sub-species ofHomo sapiens who have undergone endemic dwarfism owing to their formative heritage on isolated island locations.     

Recent advances in South American mammalian paleontology

Recently discovered deposits containing terrestrial mammal fossils, together with multidisciplinary studies of classical sequences, have yielded dramatic insights into the biotic and environmental history of South America. Notable advances include several new fossil primate taxa, an improved chronology of two major immigration events (caviomorph rodents and new world monkeys), documentation of the oldest mammalian faunas dominated by grazing taxa (which suggests that grasslands appeared at least 15 million years earlier than on other continents), evidence of early biogeographical provinciality within South America, and improved sampling of the best known Cenozoic tropical South American paleofauna.     

A taxonomic distance applicable to paleontology

A general Hausdorff-like metric on sets is presented with applications to paleontological “dissimilarity measures.” The distances between taxa represented by living organisms and/or fossil material are obtainable simply and independently of the nature of the characteristics used to define the taxonomic units. In particular, linear independence of the measured anatomical characters is not required.