The Phylogenetic Affinities of the Enigmatic Mammalian Clade Gondwanatheria

Gondwanatheria is a group of extinct mammals known from the Cretaceous and Paleogene of Gondwana. Resolution of the phylogenetic affinities of gondwanatherians has proven problematical, with the group currently considered Mammalia incertae sedis. We briefly review the morphology of known gondwanatherians, and argue that isolated upper premolars and a partial dentary preserving a blade-like p4 originally referred to the ferugliotheriid gondwanatherian Ferugliotherium windhauseni but subsequently identified as Multituberculata incertae sedis do indeed belong to F. windhauseni. We also suggest that the recently described ?cimolodontan multituberculate Argentodites coloniensis, based on an isolated lower premolar, may in fact be an unworn p4 of Ferugliotherium or a closely related taxon. We present the first phylogenetic analyses to include gondwanatherians, using maximum parsimony and Bayesian methods. Both methods place Ferugliotherium and sudamericid gondwanatherians in a clade with cimolodontan and “plagiaulacidan” multituberculates, although relationships within this clade are largely unresolved. The Gondwanatheria + Multituberculata clade supported here may reflect the convergent evolution of similar dental features, but it is the best supported hypothesis based on currently available data. However, denser sampling of multituberculate taxa and the discovery of more complete gondwanatherian fossils will be required to clarify the precise relationship between gondwanatherians and multituberculates, specifically to determine whether or not gondwanatherians are members of Multituberculata. We hypothesize that the anterior molariforms of sudamericid gondwanatherians evolved from blade-like precursors similar to the p4 of Ferugliotherium, possibly in response to the appearance of grasses in Gondwana during the Cretaceous.     

Morphology of the middle ear of golden moles (Chrysochloridae)

The middle ear structures of nine species of golden moles (family Chrysochloridae) were examined under the light microscope. Auditory structures of several of these species are described here for the first time in detail, the emphasis being on the ossicular apparatus. Confirming previous observations, some golden moles (e.g. Amblysomus species) have ossicles of a morphology typical of mammals, whereas others ( Chrysospalax , Chrysochloris , Cryptochloris and Eremitalpa species) have enormously hypertrophied mallei. Golden moles differ in the nature and extent of the interbullar connection, the shape of the tympanic membrane and that of the manubrium. The stapes has an unusual orientation, projecting dorsomedially from the incus. It has been proposed that hypertrophied ossicles in golden moles are adapted towards the detection of seismic vibrations. The functional morphology of the middle ear apparatus is reconsidered in this light, and it is proposed that adaptations towards low-frequency airborne hearing might have predisposed golden moles towards the evolution of seismic sensitivity through inertial bone conduction. The morphology of the middle ear apparatus sheds little light on the disputed ordinal position of the Chrysochloridae.     

Age and perception of dental appearance and tooth colour

Objectives: To determine the prevalence of satisfaction with dental appearance and own tooth colour in the UK and investigate the impact of ageing on these perceptions. Methods: Data about ageing and satisfaction with dental appearance and tooth colour was gathered by means of a questionnaire completed at face‐to‐face interview. The questionnaire was first tested and then used by the Office of National Statistics (ONS) in a stratified random sample of adults drawn from the UK. A total of 3384 adults were interviewed. Results: Three quarters of the population were satisfied with their own dental appearance and two‐thirds were satisfied with their tooth colour. Subjects over the age of 55 were significantly more likely to be satisfied with their dental appearance and tooth colour (p < 0.05) compared with younger age groups. Conclusions: Ageing is not necessarily associated with negative self‐perception of dental appearance or tooth colour. Greater dissatisfaction with dental appearance or colour in younger ages may suggest that perceived appearance is linked to cognitive factors other than social or cultural ones.     

Biohistorical approaches to “race” in the United States: Biological distances among African Americans,European Americans,and their ancestors

Folk taxonomies of race are the categorizations used by people in their everyday judgments concerning the persons around them. As cultural traditions, folk taxonomies may shape gene flow so that it is unequal among groups sharing geography. The history of the United States is one of disparate people being brought together from around the globe, and provides a natural experiment for exploring the relationship between culture and gene flow. The biohistories of African Americans and European Americans were compared to examine whether population histories are shaped by culture when geography and language are shared. Dental morphological data were used to indicate phenotypic similarity, allowing diachronic change through United States history to be considered. Samples represented contemporary and historic African Americans and European Americans and their West African and European ancestral populations (N = 1445). Modified Mahalanobis' D² and Mean Measure of Divergence statistics examined how biological distances change through time among the samples. Results suggest the social acceptance for mating between descendents of Western Europeans and Eastern and Southern European migrants to the United States produced relatively rapid gene flow between the groups. Although African Americans have been in the United States much longer than most Eastern and Southern Europeans, social barriers have been historically stronger between them and European Americans. These results indicate that gene flow is in part shaped by cultural factors such as folk taxonomies of race, and have implications for understanding contemporary human variation, relationships among prehistoric populations, and forensic anthropology. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc.     

Correlation of carnassial tooth size and body weight in recent carnivores (mammalia)

The correlation between the lower carnassial crown area and the body weight is examined for modern carnivores. It is very high, but the ursids and felids show a relationship different from the other carnivore families. Some exceptions are discussed. The possibility of predicting body weight for fossils is given.     

Biology, not environment, drives major patterns in maximum tetrapod body size through time

Abiotic and biological factors have been hypothesized as controlling maximum body size of tetrapods and other animals through geological time. We analyse the effects of three abiotic factors--oxygen, temperature and land area--on maximum size of Permian-Jurassic archosauromorphs and therapsids, and Cenozoic mammals, using time series generalized least-squares regression models. We also examine maximum size growth curves for the Permian-Jurassic data by comparing fits of Gompertz and logistic models. When serial correlation is removed, we find no robust correlations, indicating that these environmental factors did not consistently control tetrapod maximum size. Gompertz models--i.e. exponentially decreasing rate of size increase at larger sizes--fit maximum size curves far better than logistic models. This suggests that biological limits such as reduced fecundity and niche space availability become increasingly limiting as larger sizes are reached. Environmental factors analysed may still have imposed an upper limit on tetrapod body size, but any environmentally imposed limit did not vary substantially during the intervals examined despite variation in these environmental factors.