颜面扁平度的变异和山顶洞人类化石的颜面扁平度

扁平的颜面这一蒙古人种的颅骨特征可上溯到直立人时代。在新石器时代,颜面扁平度总的来看华北地区的要比华南的稍大些,但这种南北差别并无严格的地理界线;在现代,这种地理上的差别更不明显。山顶洞人类头骨化石的过小的颜面扁平度很可能是受外来“基因流”的影响的结果。     

Seasonal and local spatial patterns in the upper thermal limits of corals on the inshore Central Great Barrier Reef

 Experimental studies of the upper thermal limits of corals from Orpheus Island, an inshore reef in the central Great Barrier Reef, show that Acropora formosa has a 5-day 50%-bleaching threshold of between 31 and 32 °C in summer, only 2 to 3 °C higher than local mean summer temperatures (29 °C). Summer bleaching thresholds for Pocillopora damicornis and A. elseyi were 1 °C higher (between 32 and 33 °C). The winter bleaching threshold of Pocillopora damicornis was 1 °C lower than its summer threshold, indicating that seasonal acclimatisation may take place. This seasonal difference raises the possibility that at least some corals may be capable of short-term thermal acclimatisation. Neither P. damicornis nor A. elseyi showed habitat-specific (reef flat versus reef slope) differences in bleaching thresholds. Further, colonies of P. damicornis collected from sites 3 km apart also showed no difference in bleaching threshold despite populations of this species responding differently at these two sites during a natural bleaching event. The bleaching thresholds determined in this study are best considered as the maximum tolerable temperatures for local populations of these species because they were determined in the absence of additional stressors (e.g. high light) which often co-occur during natural bleaching events. We consider the 5-day 50% bleaching thresholds determined in these experiments to be fair indicators of upper thermal limits, because >50% of a sample population died when allowed to recover in situ. We found a delay of up to a month in the bleaching response of corals following thermal stress, a result that has implications for identifying the timing of stressful conditions in natural bleaching events. Accepted: 26 May 1999     

岷江上游暗针叶林采伐迹地人工混交林群落结构

对四川岷江上游高山峡谷区暗针叶林采伐迹地年龄为２０－４０年的人工混交林群落结构进行了研究,结果是：（１）群落中各层次物种盖度的大小相互影响,相互制约,而林下（各）层次物种盖度的大小主要取决于其上（各）层盖度（或郁闭度）的大小,（２）人工重建的群落所能容纳的物种数及物种在群落中的分布状况主要取决于乔木物种郁工,海拔高度及经营强度。（３）群落中出现大量的耐荫植物,先锋灌丛植物已被抑制或淘汰,（４）乔木     

Ulphaceaster sarthacensis,nouveau genre et nouvelle espèce d’échinide Archiaciidae du Cénomanien (Sarthe,France)

A new genus and a new species of the echinoid family Archiaciidae from Cenomanian deposits in Sarthe (Paris Basin, France) are described. The genus Ulphaceaster nov. gen. can be distinguished from other archiaciids by its anterior ambulacrum, which is located in a deep groove running from the peristome to the apex where the test enlarges in a tea-spoon shape. The apical rostrum is taller and more slender than for species of the close genus Claviaster. The species Uphaceaster sarthacensis sp. nov. is known from the Saint-Ulphace locality only (Sables et Grès de Lamnay Formation, La Garenne quarry), where it is found in shallow marine sandy limestones, from infralittoral deposit environments.     

Upper body accelerations during planned gait termination in young and older women

Transitory tasks, such as gait termination, involve interactions between neural and biomechanical factors that challenge postural stability and head stabilization patterns in older adults. The aim of the study was to compare upper body patterns of acceleration during planned gait termination at different speeds between young and older women. Ten young and 10 older women were asked to carry out three gait termination trials at slow, comfortable and fast speed. A stereophotogrammetric system and a 15-body segments model were used to calculate antero-posterior whole-body Center of Mass (AP CoM) speed and to reconstruct the centroids of head, trunk and pelvis segments. RMS of three-dimensional linear accelerations were calculated for each segment and the transmission of acceleration between two segments was expressed as a percentage difference. Older women reported lower AP CoM speed and acceleration RMS of the three upper body segments than young women across the three speed conditions. A lower pelvis-to-trunk attenuation of accelerations in the transverse plane was observed in older compared to young women, and mainly in the medio-lateral direction. As possible explanations, older women may not need to reduce acceleration as young women because of their lower progression speed and the subsequent acceleration at upper body levels. On the other hand, older women may prioritize a decrease in the whole body progression speed at expense of the involvement of upper body segments. This limits the attenuation of the accelerations, particularly in the transverse plane, implying an increased dynamic unbalance in performing this transitory task.     

L’impact de l’environnement sur l’évolution biologique et culturelle dans les périodes de transition en Préhistoire : Paléolithique ancien/moyen et Paléolithique moyen/supérieur

This paper deals with the environmental changes during two important transitional periods, namely Lower/Middle Paleolithic and Middle/Upper Paleolithic transitions, and with their impact on biological and cultural evolutions, in the context of central, eastern and northwestern Europe, where ice-sheet transgressions induced particular paleogeographical and paleoecological conditions. Another country was studied too, the Balkans, a privileged area for bilateral contacts between Europe and the Near East.     

Manus-only titanosaurid trackway from Fumanya (Maastrichtian, Pyrenees): further evidence for an underprint origin

The origin of manus-only and manus dominated sauropod trackways has been a matter of intense debate since two hyphothesis exist: (a) manus-only and manus-dominated trackways result from a 'swimming' sauropod, and (b) they result from a selective underprint phenomenon that only leaves the manus recorded. Several new sauropod trackways are reported in the Fumanya tracksite area (Maastrichtian), in SE Pyrenees, where both tracks and undertracks are found on the same stratigraphic bedding surface. In one of the trackways, footprint morphology together with the trackway pattern displays a clear succession of manus-only impressions attributed to a sauropod dinosaur in a walking gait. The ichnological comparison between the manus-only trackway with the other complete trackway (manus-pes) display an identical distribution of the manus pattern. This fact clearly points towards an underprint phenomenon as the origin for manus-only trackways, since it is rather unlikely that the same pattern would completely match different locomotion behaviours such as walking and swimming. Therefore, we suggest an interpretation based on the differential loading between the hindfoot and the forefoot on an upper stratigraphic track-level, for the studied manus-only trackway. □ Fumanya tracksite, manus-only trackways, titanosaurs, trackway pattern, underprint, Upper Cretaceous.     

Microbial encrustations from the Middle Oxfordian-earliest Kimmeridgian lithofacies in the Prebetic Zone (Betic Cordillera, southern Spain): characterization, distribution and controlling factors

Two main types of microbial encrustation were identified in Middle Oxfordian to lowermost Kimmeridgian deposits in the Prebetic Zone (southern Spain), showing existing relationships between skeletal content, fabric and morphology of these organosedimentary structures. Laminated planar and concentric encrustations relate to peloidal fabrics (mainly constituted of microbes = microbial laminated fabrics s. str. and microbial oncoids s. str.), as well as to dense microbial fabrics periodically colonized by encrusting foraminifera (microbial laminated fabrics with nubeculariids and microbial oncoids with nubeculariids). Sedimentation rates, substrate stability and grain size, as well as illumination, influenced microbial growth pattern as major controlling factors in low-energy conditions, and forced palaeogeographic and stratigraphic patterns of distribution. Significant encrustation was identified in terrigenous-poor lithofacies from the middle (Transversarium-Bifurcatus zones) to the outer (Transversarium-Bimammatum zones) shelf in the Prebetic Zone. Rare-to-absent encrustation characterized terrigenous-rich deposits (Bimammatum and Planula zones) in the area.     

Population genetic diversity of Prenant’s schizothoracin, Schizothorax prenanti, inferred from the mitochondrial DNA control region

Wild populations of Prenant’s schizothoracin, Schizothorax prenanti, were collected from the Qingyi, Dadu, and Muli rivers in upper reaches of the Yangtze River. Genetic variation and population structure were examined based on analysis of the mitochondrial DNA control region. Nucleotide sequence analysis defined 30 haplotypes in 41 individuals. The nucleotide and haplotype diversities were very high, and genetic distances between the Dadu and Qingyi populations were much smaller than between either of them and the Muli population. The analysis of molecular variance demonstrated that most variation occurred within samples, and the differentiation between Muli and Dadu or Qingyi was significant. Estimates of gene flow indicated reproductive isolation between Muli and the other populations, and this divergence might be related to geographical location. The results are mostly consistent with the findings from AFLP analysis and also suggested considerable genetic diversity of the populations in the Muli, Dadu, and Qingyi rivers.