贵州八郎寒武系清虚洞组三叶虫Protoryctoce phalus arcticus的蜕壳研究  

EXUVIATION OF TRILOBITE PROTORYCTOCEPHALUS ARCTICUS FROM THE CAMBRIAN TSINGHSUTUNG FORMATION OF GUIZHOU

作　　者：孙宗元[1] 杨兴莲[1,2] 赵元龙[1] 郑昊林[1] 朱雅杰[1] 

机构地区：[1]贵州大学资源与环境工程学院,贵阳550003 [2]现代古生物学和地层学国家重点实验室,中国科学院南京地质古生物研究所,南京210008

出　　处：《古生物学报》2013年第2期256-264,共9页Acta Palaeontologica Sinica

基　　金：国家重点基础研究发展计划(2013CB835002);国家自然科学基金(40902003;40672018);贵州省科技特别基金项目(黔科机字2007-4004);贵州省科技基金项目(黔科合J字[2011]2035号);贵州省国际科技合作项目(黔科合外G字[2010]7001);现代古生物学和地层学国家重点实验室(113109)联合资助

摘　　要：研究标本均为Protoryctoce phalusarcticus Geyer and Peel,2011的蜕壳标本,保存于贵州剑河八郎村寒武纪第2世的清虚洞组中,头部、胸部、尾部都得以保存,且胸部与尾部未分离。该类三叶虫可能经历了3个时期的蜕壳过程:1)头部进行上下弯曲,水阻力造成两侧活动颊受到的压力明显大于头盖,这种压力可能导致面线出现裂缝,之后海水通过裂缝进入头部,新头部活动范围增大,并利用水压力降低旧头盖与新头盖的连接程度;2)虫体携带着旧胸尾及其他相连接的部分向前爬行,并在短距离内将旧头盖与虫体分开;3)虫体通过不同的爬行方式摆脱旧壳。本文还重点讨论三叶虫蜕壳过程中首断裂缝的产生、胸尾是否分离的原因、头部运动方向对旧壳保存的影响、以及水动力和水压力在蜕壳过程中的作用。该研究补充oryctocephalids三叶虫的蜕壳研究,为三叶虫的系统演化、个体发育的再研究提供一定的支撑。The shelling processes of trilobites are important for ontogeny. Moulting specimens of Prowryctocephalusarcticus （Geyer and Peel, 2011） are described here. They were collected from the Cambrian age Tsinghsutung Formation, Guizhou. Their cephalon, thorax and pygidium are preserved, and thoracic and pygidial shields are articulated. The trilobite exuvial configuration emerged after the following： 1）The trilobite bent the cephalon downwards and upwards. The water resistance caused by the pressure on both sides of free cheeks is significantly larger than that on cranidium. This pressure may lead to fissure on the facial sutures, and then seawater drip into the cephalon through the fissure. This increases the size of new cephalon making it to lose the connection between the old cranidium and the new cranidium through the water pressure. 2）The trilobite body, with the old thoracopygon and other connected parts, crawls forward, separates from the old cranidium in a short distance. 3 ）The trilobite, through in different ways, crawls from the old shell. This paper focuses on the following： Why does their cephalon crack？ Why is it that their thoracic shield and pygidial shield do not separate？ How does the direction of their cephalon＇s movement influence their old shells ＇ preservation？ What function does the water pressure perform in the process of exuviations？ The exuvial materials of Protoryctocephalus arcticus （Geyer and Peel, 2011） provide new data for studies on systematic evolution and ontogeny of related trilobites.

关 键 词：蜕壳 掘头虫类三叶虫 清虚洞组 寒武系 

分 类 号：Q915[天文地球—古生物学与地层学]