【作者】 雷倩萍；

【导师】 万晓樵；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2010， 硕士

【摘要】 澄江化石库是显生宙以来地球上已知最早的多细胞动物群之一,它以丰富的化石种类和精美的保存质量,成为“窥探”寒武纪生命大爆发的绝佳窗口。目前,除藻类、遗迹和粪便化石外,澄江动物群共描述160多属,180多种化石。包含现今原口动物中几乎所有的主要门类,更重要的是还发现了后口动物超门中的所有类别的早期代表。本次研究的对象主要是澄江化石库中特定类群——固着类。此类群营固着底表或他物上生活。具体的固着型动物包括:海绵动物门若干属种;刺胞动物包括先光海葵(Xianguangia)、原始管虫(Archotuba);腕足动物龙潭村贝(Longtancunella)、西山贝(Xishanella)、顾托贝(Kutorgina)、滇东贝(Diandongia)等;一些分类位置不明确的如开腔骨类(chancelloriids);瘤状杯形虫(Cotyledion tylodes);火炬虫(Phlogites);高足杯虫(Dinomischus);后口动物长江海鞘(Cheungkangella)等。笔者对云南昆明地区早寒武世地层开展了野外调查和化石采集。目的是初步探讨固着型动物的起源、演化问题。固着方式的起源不仅反映了后生动物的生态及生活方式,而且与生物矿化骨骼出现有比较密切的关系。此外对于探讨后生动物生长发育过程及浮游幼虫的生态也能提供一定信息。固着型动物的幼虫大多营浮游生活,这不但反映了其祖先最初的生活方式,而且对其后期的生存发展更有着重大意义。浮游幼虫可以在较短的浮游期内主动找寻合适的基底,为不久后的固着生活做好准备。对澄江化石库中众多固着类标本的研究显示,大多类型偏爱固着于其他动物的外壳等硬体部分之上。我们暂且把其中的固着基底类型分为两大类:生物矿化硬体基底和非生物基底。而前者较之后者更具优势。常见的生物硬体基底有:三叶虫的活动颊、固定颊、轴刺;腕足动物的壳体;软舌螺壳体等。寒武纪早期应是生物固着方式的重大演化阶段,体现了固着方式由早期仅有的非生物基底固着向生物硬体固着的演化发展,这也与寒武纪初大量生物矿化骨骼出现密切相关。早寒武世固着方式的多样化对此后后生动物的辐射演化,生态多样性也有深远影响。共可划分出三大阶段,分别为:Ediacaran期;梅树村期;筇竹寺期。更多还原

【Abstract】 The Chengjiang Largert?tte represents one of the earliest multicellular faunas on earth since the Phanerozoic eon. It becomes the most excellent window for deciphering the Cambrian explosion because of its abundant fossils and exquisite preserving quality. At present, there are over 180 species of 160 genera in Chengjiang, besides alga, trace fossils and coprolites. It contains almost every primary phyla of protostomes nowadays, more importantly, early representatives of the duterostomes were also found in the largert?tte.The targets of this study are mainly the special group—sessile epifauna. They live on the substrate or on other shells, including: several species of sponge; cnidarians, such as Xianguangia、Archotuba; brachiopods as Longtancunella、Xishanella、Kutorgina、Diandongia; some problematica such as chancelloriids; Cotyledion tylode; Phlogites; Dinomischus; duterostomes as Cheungkangella.The author has done some field investigation and fossil-collection concerning the lower Cambrian strata in Kunming, Yunnan, in order to discuss the origin and evolution of the sessile epifauna. The origin of sessility not only reflects the ecology and living habits of the metazoans, but also has close relationship with the presence of the biomineralized or slerotized. Moreover, it is meaningful for discussing the growing processes and ecology of the planktonic larvae. Most larvae of the sessile epifauna are all pelagic, which reflects their ancestral habit and also has important significance during their later growth and reproduction. The planktonic larva could seek for appropriate substrate actively during its short pelagic period, and make good preparation for later sessile stage.As the study on many specimen of sessile epifauna indicated, most of them prefer to attach to other shells. Now we divide the attaching substrates into two kinds: sclerotized substrates and abiotic substrates. However the former is more advantageous than the latter. The common sclerotized substrates are: trilobite librigena and fixigena, axial spine; brachiopod shells; hyoliths and so on. Cambrian is a significant period for the evolution of sessile epifauna, eyewitnessing the evolution from the only abiotic substrate to the sclerotized substrates, which is also related to the appearance of the abundant biomineralized and slerotized skeleton during Cambrian.The diversification of attachment during early Cambrian plays a great role in the subsequent radiation of metazoan and the ecological diversity. There are three periods of attachment evolution: Ediacaran; Meishucunian; Qiongzhusian.更多还原