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陕南寒武纪梅树村期西乡生物群中的管状化石数量丰富,本文对其中的三类主要化石类型:软舌螺、似软舌螺类和阿纳巴管类进行了深入研究。其中软舌螺主要为圆管螺目,属于寒武纪软舌螺演化的第一阶段,且化石具有不同的壳体结构:主要分为单层壳和多层壳两大类,多层壳根据截面又可分为同心与偏心两类。单层壳与同心多层壳可能属于原生结构;偏心多层壳属于次生结构。对上述各类结构进行了分类统计,其中的单层壳与次生多层壳居多,并推测原生多层壳体的出现可加固管体,是地球早期生物为应对同期食肉动物所进化出的生存对策。似软舌螺类的两属:小软舌螺属及小钻孔螺属在此生物群中均有发现。西乡生物群中的阿纳巴管类主要为Anabarites trisulcatus,Aculeochrea tripartitus和Anabarites isiticus,其中Anabarites isiticus的化石壳体表面具有细密生长纹,生长纹可明显分为较粗与较细两类,二者相间排列、重复出现,体现了生物不同的生长周期。
There are abundant tubular fossils in the Xixiang biota of the Meishucun period in the southern Shaanxi province. In this paper, three types of fossil fossils, Soft lingula, Soft lingual snails and Ananas, were studied in depth. Among them, the soft-headed snail is mainly a pipe snail, belonging to the first stage of the evolution of the soft tongue in the Cambrian, and the fossil has a different shell structure. The fossil is divided into two major categories: the single-shell shell and the multi-shell shell, According to the cross section can be divided into two types of concentric and eccentric. Single shell and concentric multi-shell may belong to the original structure; eccentric multilayer shell belongs to the secondary structure. According to the statistics of the above structures, the number of single-shell and secondary multi-shell is the most, and it is speculated that the appearance of primary multi-shell can reinforce the tube, which is the early evolution of the earth in response to the same carnivore Survival strategy. The two genera that belong to the genus Soft lingual snails: the Lesser soft lingual snails and the small bore snails are found in this biome. The Anabarites trisulcatus, Aculeochrea tripartitus and Anabarites isiticus in the Xixiang biota. The fossil shells of Anabarites isiticus have fine growth patterns and the growth patterns can be divided into two types: coarse and thin, Interphase, repeated appearance, reflects the different biological growth cycle.