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Mammalian Orders (mammalian + order)
Selected AbstractsScaling of body temperature in mammals and birdsFUNCTIONAL ECOLOGY, Issue 1 2008Andrew Clarke Summary 1We examine variation associated with phylogeny in the scaling of body temperature in endotherms, using data from 596 species of mammal and 490 species of bird. 2Among higher groups of mammals there is statistically significant scaling of body temperature with mass in Marsupialia (positive), Ferae and Ungulata (both negative). In mammalian orders where data are available for at least 10 species, scaling is negative in three orders (Carnivora, Erinaceomorpha and Artiodactyla), positive in one (Chiroptera) and not significant in seven others. There is no relationship apparent between the scaling of body temperature and the existence of gut fermentation. As expected, monotremes exhibit the lowest body temperatures, but within marsupials diprotodonts have a mean body temperature higher than several placental groups; the traditional ranking of body temperatures in the sequence monotremes , marsupials , placentals is thus misleading. 3In birds, scaling relationships are significant only for Ciconiiformes (strongly negative) and Passeriformes (weakly positive). 4When allowance is made for phylogenetic effects, there is no significant relationship between temperature in body mass in mammals overall, but an inverse and almost significant relationship in birds. 5This study indicates a complex relationship between body mass, body temperature and metabolic rate in mammals and birds, mediated through ecology. [source] Microscopic configurations on the bare-bone surfaces of mammalian synovial jointsINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2001A.E.W. MilesArticle first published online: 30 NOV 200 Abstract The smoothness characteristic of synovial joint surfaces of bare bones is shown to be an illusion; low-power microscopy of young adult human bones from interments revealed, on the surfaces of a variety of synovial joints, a system of basically hemispherical elevations, often united as short chains or groups. This system was also found on joints of a variety of species of six mammalian orders. Under the higher magnification of scanning electron microscopy (SEM), many elevations had a pit at their summits. The bare-bone surfaces of synovial joints have a thin covering of mineralized cartilage, including its mineralizing-front, which survives taphonomic processes, as well as the preparative procedures used in the study of articular surfaces. In its formative phase, the front has the chondrocyte,columnar structure of cartilage. It is postulated here that the newly-discovered elevations arise when cartilage formation is ceasing, or becoming dormant, and that each column-unit produces a globular mineralized mass, often with a pit which had accommodated a chondrocyte. These masses may incorporate the fibre systems of the unmineralized cartilage and aid in its attachment to the bony surface. Copyright © 2001 John Wiley & Sons, Ltd. [source] Purring and similar vocalizations in mammalsMAMMAL REVIEW, Issue 4 2002G. Peters ABSTRACT The terms purr and purring have been used for vocalizations produced by a variety of mammalian species in different orders. A few other mammalian vocalizations that are structurally somewhat similar to felid purring but have been given another term have also been described in the literature. Because use of the same term implies ,sameness', which in an evolutionary sense can only mean that the vocalizations so named are homologous (= share the same ancestral vocalization type), the terms purr and purring ought to be restricted to vocalizations homologous with felid purring, and any mammalian vocalization homologous with felid purring ought to be named accordingly. According to present knowledge ,true' purring is established only in the families Viverridae and Felidae of the Carnivora. Vocalizations very similar in structure occur in matching behavioural contexts in other families of the Carnivora and several other mammalian orders. Most of these vocalization types are likely to have evolved convergently. [source] A quantitative analysis of the Eutherian orbit: correlations with masticatory apparatusBIOLOGICAL REVIEWS, Issue 1 2008Philip G. Cox Abstract The mammalian orbit, or eye-socket, is a highly plastic region of the skull. It comprises between seven and nine bones, all of which vary widely in their contribution to this region among the different mammalian orders and families. It is hypothesised that the structure of the mammalian orbit is principally influenced by the forces generated by the jaw-closing musculature. In order to quantify the orbit, fourteen linear, angular and area measurements were taken from 84 species of placental mammals using a Microscribe-3D digitiser. The results were then analysed using principal components analysis. The results of the multivariate analysis on untransformed data showed a clear division of the mammalian taxa into temporalis-dominant forms and masseter-dominant forms. This correlation between orbital structure and masticatory musculature was reinforced by results from the size-corrected data, which showed a separation of the taxa into the three specialised feeding types proposed by Turnbull (1970): i.e. ,carnivore-shear', ,ungulate-grinding' and ,rodent-gnawing'. Moreover, within the rodents there was a clear distinction between species in which the masseter is highly developed and those in which the temporalis has more prominence. These results were reinforced by analysis of variance which showed significant differences in the relative orbital areas of certain bones between temporalis-dominant and masseter-dominant taxa. Subsequent cluster analysis suggested that most of the variables could be grouped into three assemblages: those associated with the length of the rostrum; those associated with the width of the skull; and those associated with the relative size of the orbit and the shape of the face. However, the relative area of the palatine bone showed weak correlations with the other variables and did not fit into any group. Overall the relative area of the palatine was most closely correlated with feeding type, and this measure that appeared to be most strongly associated with the arrangement of the masticatory musculature. These results give a strong indication that, although orbital structure is in part determined by the relative size and orientation of the orbits, the forces generated by the muscles of mastication also have a large effect. [source] When brains expand: mind and the evolution of cortexACTA NEUROPSYCHIATRICA, Issue 3 2007Matthew T. K. Kirkcaldie Objective:, To critically examine the relationship between evolutionary and developmental influences on human neocortex and the properties of the conscious mind it creates. Methods:, Using PubMed searches and the bibliographies of several monographs, we selected 50 key works, which offer empirical support for a novel understanding of the organization of the neocortex. Results:, The cognitive gulf between humans and our closest primate relatives has usually been taken as evidence that our brains evolved crucial new mechanisms somehow conferring advanced capacities, particularly in association areas of the neocortex. In this overview of neocortical development and comparative brain morphometry, we propose an alternative view: that an increase in neocortical size, alone, could account for novel and powerful cognitive capabilities. Other than humans' very large brain in relation to the body weight, the morphometric relations between neocortex and all other brain regions show remarkably consistent exponential ratios across the range of primate species, including humans. For an increase in neocortical size to produce new abilities, the developmental mechanisms of neocortex would need to be able to generate an interarchy of functionally diverse cortical domains in the absence of explicit specification, and in this respect, the mammalian neocortex is unique: its relationship to the rest of the nervous system is unusually plastic, allowing great changes in cortical organization to occur in relatively short periods of evolution. The fact that even advanced abilities like self-recognition have arisen in species from different mammalian orders suggests that expansion of the neocortex quite naturally generates new levels of cognitive sophistication. Our cognitive and behavioural sophistication may, therefore, be attributable to these intrinsic mechanisms' ability to generate complex interarchies when the neocortex reaches a sufficient size. Conclusion:, Our analysis offers a parsimonious explanation for key properties of the human mind based on evolutionary influences and developmental processes. This view is perhaps surprising in its simplicity, but offers a fresh perspective on the evolutionary basis of mental complexity. [source] | ||||||||||