5 resultados para skull

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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Bamboo bats are a group of small bats with unique skull and morphology. They roost inside hollow bamboo stems in tropical and subtropical Asia and the Ambon Islands (Moluccas). We examined 53 specimens of Tylonycteris from southern and southwestern China. Comparisons of skull and external characteristics, pelage color, shapes of thumbpads and footpads, and statistical analysis of cranial measurements revealed that specimens from Damenglong, Jinghong County, Xishuang-banna, Yunnan, are distinctly different from the other two species of Tylonycteris described so far. The Yunnan specimens are the smallest in size; have dark blackish brown pelage color; and have larger upper premolars, smaller first lower premolars, and longer C-M-3. They are sympatric with the previously described species. Here we review the genus Tylonycteri and describe a new species, Tylonycteris pygmaeus, from the Yunnan material.

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As a first step in reviewing the classification of the two stump-tailed macaque species, Macaca arctoides and M. thibetana, as compared with other species of the genus Macaca, 72 linear dental and cranial variables of 11 macaque species were examined by morphometric analyses. The results indicate that the two stump-tailed species are the largest of the macaques and although rather similar overall, they exhibit significant differences in the pattern of variation in most of the five skull regions as shown by Principal Components and Canonical Variate Analyses. Euclidean Distances based on Canonical Variate scores indicate that the females of M. arctoides and M. thibetana are more widely separated than eight other pairs of macaque species, and that the separations of the respective males are greater than those of three other pairs of species. These findings are consistent with FOODEN's classification of the stump-tailed macaques as two separate species (FOODEN, 1976; FOODEN et al., 1985). The present results suggest, as other researchers have proposed on the basis of external features, biochemistry and genetics, that the two stump-tailed macaque species and M. assamensis are closely related. The results also tentatively imply associations with M. fuscata and M. sylvanus but these require further study. The findings have implications for the assessment of the various Chinese Pleistocene macaque fossils.

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This thesis focuses on the study of the geomagnetic orientation and navigation of homing pigeon and migrating bats. Magnetic minerals, possibly the base of the “magnetoreceptors”, which can perceive the magnetic information from geomagnetic field, are studied using advanced mineral magnetic methods in combination of non-magnetic techniques. In addition, the mechanism of magnetite biomineralization in organism has been probed through the formation of ferritin under laboratory-controlled conditions. A series of magnetic measurements of selected pigeon samples found the biogenic magnetite particles. a significant rapid decay of SIRM5K in the interval of 5–20 K on both zero-field cooled and field cooled warming curves suggests the dominance of superparamagnetic particles in the samples. Additionally, we noted that the content of magnetite particles in the male and the female are different. It is also found that bats contain magnetite. The results of room temperature magnetic measurements of Rhinolophus ferrumequinum and Chaerophon plicatus samples indicates there are magnetite in the heads of bats. The concentration of magnetic materials in the brain is higher than that in the skull. The results of low temperature magnetic measurements in Nyctalus plancyi samples show that the head may contain a small quantity of magnetite particles. In order to study the magnetite biomineralizaiton, ferritin was reconstituted. The results of electron nanodiffraction patterns indicate that the dominant mineral phases in the reconstituted ferritin are ferrihydrite, which is similar to that in the native ferritin. The blocking temperature (TB) is near 20K. A series of magnetic hysteresis at low temperatures (3-21K) show the wasp-waisted hysteresis loop. This can be interpreted by either grain size effects (SP + SD) or different coercivities minerals.