Lives morphologies and body development of Cambrian nemathelminths and arthropods, a testtool for phylogeny analyses and hypotheses

保存完好的各种后生动物分类群的早期代表主要有四个来源：下寒武统成江Lagerstätten、下寒武统天狼星帕塞特Lagerstätte、中寒武统伯尔吉斯页岩Lagerstätten和下至上寒武统奥斯滕¿Lagerstätten。这些Lagerstätten的化石对我们了解早期后生动物的进化以及当时后生动物开始辐射的形态和生活方式做出了重大贡献。许多问题都得到了圆满的解决，但仍有一个主要问题：最大的动物分类单元节肢动物系统地归属于何处？哪个是最近的亲戚？七年前，长期存在的与环节动物姐妹群关系的教条受到质疑，并提出了线虫-节肢动物关系的新观点。直到今天，这个问题仍未得到解决。以上面提到的线虫和节肢动物化石lagerstätten的代表为重点，我们将研究原始材料，特别强调结构和功能设计以及身体发育。这包括最重要和最关键的节段进化方面，内部连续中胚层细分的外部表达，身体标记化和附属物形成，部分特征很可能在线虫中不存在。我们的特别目标是将从这些活的形态中积累的数据作为优先计划中不同其他工作组产生的系统发育假设的测试工具。

There are four major sources of exquisitely preserved early representatives of various metazoan taxa: the Lower Cambrian Chengjiang Lagerstätten, the Lower Cambrian Sirius Passet Lagerstätte, the Middle Cambrian Burgess Shale Lagerstätten and the Lower to Upper Cambrian ¿Orsten¿ Lagerstätten. The fossils of these Lagerstätten have contributed significantly to our knowledge of early metazoan evolution and the morphologies and life styles developed at the time, when metazoan life began to radiate. Many questions have become satisfactorily resolved, but one of the major questions remained: Where do the arthropods, the largest animal taxon belong to systematically? Which is the closest relative? Seven years ago, the long-standing dogma of a sister-group relationship with annelids was questioned and the new idea of a nemathelminth-arthropod relationship put forward. Still today, this is not resolved. Focusing on representatives of nemathelminths and arthropods from the fossil lagerstätten mentioned above, we will investigate original material with particular emphasis on structural and functional design and body development. This includes the important and most critical aspects of segment evolution, the external expression of internal serial mesoderm subdivision, body tagmatisation, and appendage formation, features partly most likely primary absent in nemathelminths. Our particular aim is to present the data accumulated from these lived morphologies as a test tool for phylogeny hypotheses resulting from the different other work groups within the Priority Programme.