Lower Cambrian yolk-pyramid embryos from Southern Shaanxi, China

TheCambrianexplosioniswidelyacceptedasthesuddenappearanceofnumerousbilateriananimalphylaatornearthebeginningofCambriantime[1,2 ] .The 5 30 million year oldMaotianshanShalefaunacontainstheoldestgoodwhole bodyfossilsofbilateri ans,documentinganincreasingnumberofpresent dayanimalphyla[3,4 ] orsubphyla[5] (evenincludingvertebrates[6～ 8] aswell)knownfromLowerCambri an .ThebeginningoftheCambrianperiodisdatedat5 43millionyearsago ,whenthefirstlargeandelabo ratefossilburrowstogetherwiththemicrosco…     

Phylogeny and life habits of Early Arthropods-Predation in the Early Cambrian Sea

We investigated two new arthropods from the Maotianshan-Shale fauna of southern China in the course of our research on life strategies, particularly predation, in Early Cambrian marine macrofaunal biota. One form clearly belongs to the so-called "great-appendage" arthropods, animals that were, most likely, active predators catching prey with their first pair of large, specialized frontoventral appendages. Based on this, we hypothesize that the new species and many others, if not all, of the "great-appendage" arthropods were derivatives of the chelicerate stem lineage and not forms having branched off at different nodes along the evolutionary lineage of the Arthropoda. Rather, we consider the "great-appendage" arthropods as belonging to a monophyletic clade, which modified autapomorphically their first pair of appendages (antennae in general arthropod terminology) into raptorial organs for food capture. The second new form resembles another Maotianshan-Shale arthropod, Fuxianhuia protensa, in sharing a head made of only two separate segments, a small segment bearing oval eyes laterally, and another bearing a large tergite, which forms a wide shield freely overhanging the subsequent narrow trunk segments. This segment bears a single pair of rather short anteriorly directed uniramous appendages, considered as the "still" limb-shaped antennae. Particularly the evolutionary status of head and limbs of these two forms suggests that both are representatives of the early part of the stem lineage toward the crown-group of Arthropoda, the Euarthropoda. These forms appear rather unspecialized, but may have been but simple predators. This adds to our hypothesis that predation was a common, if not dominant feeding strategy in the Cambrian, at least for arthropods.     

青少年饮酒:多种研究方法的综合应用

描述了综合运用定性和定量方法对中国青少年饮酒问题所进行的研究。使用文化人类学中的定量方法对三个已知可预测行为的心理学变量进行初步的小样本研究。这三个心理学变量是:青少年对饮酒行为后果的期望(饮酒期望),青少年对中国传统文化和西方文化所持的观点(文化取向),以及青少年在处理饮酒压力方面所表现的信心(自我效能)。定性研究所获得的资料被用来设计问卷,测量饮酒期望,文化取向和自我效能。定量数据的调查在大样本青少年人群中进行。统计分析表明,这些问卷能够发现饮酒者和不饮酒者在饮酒期望、文化取向、自我效能方面的差别。对于调查数据进行深入分析的结果,将为政策的制订和健康教育项目的设计指明方向,降低青少年的饮酒风险。