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首页> 外文期刊>Acta Palaeontologica Polonica >Phyletic evolution and iterative speciation in the persistent Pristiograptus dubius lineage
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Phyletic evolution and iterative speciation in the persistent Pristiograptus dubius lineage

机译：持续的Pristiograptus dubius世系的系统进化和迭代物种形成

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摘要

The paper focuses on patterns of the evolution of the simplest and longest-ranging (approximately 18 Ma) Silurian graptolite Pristiograptus dubius. The Pristiograptus dubius species group consists of the P. dubius stem lineage repre- sented by a sequence of a number of subspecies displaying only small morphological changes as well as derivative species produced from the stem lineage by means of iterative speciation. This long raging graptolite lineage is the only one, apart of one retiolitid, which survived the most severe environmental event for graptolites, the Cyrtograptus lundgreni Event. Based on three-dimensional, isolated material two P. dubius groups taxa are distinguished. One group has an obtuse angle between the thecal lip and the succeeding thecal wall, the second group has a right or acute angle. Other characters differentiating P. dubius forms are: the shape of the apertural lips, differences in rhabdosome shape and size, and a different number of sicular rings. Sixteen species and subspecies of Pristiograptus from the East European Platform, Poland and Lithuania are discussed. Five new subspecies P. dubius magnus, P. dubius paezerensis, P. dubius praelodenicensis, P. dubius postfrequens, and P. dubius postmagnus are proposed.
机译：本文重点研究了志留系笔石质笔石Pristiograptus dubius的最简单和范围最长（大约18 Ma）的演化模式。 Pristiograptus dubius物种组由P. dubius茎谱系组成，这些谱系由一系列只显示小形态变化的亚种序列以及通过迭代物种形成从茎谱系产生的衍生物种组成。这种长久以来肆虐的角砾岩世系是仅有的一种维甲酸，在角砾岩最严重的环境事件（Cyrtograptus lundgreni事件）中幸存下来。基于三维隔离材料，区分了两个杜氏假单胞菌类群。一组在鞘唇和后继的鞘壁之间具有钝角，第二组具有直角或锐角。区别于毕氏假单胞菌的其他特征还包括：孔眼唇的形状，横纹体的形状和大小的差异以及不同数量的突突环。讨论了东欧平台，波兰和立陶宛的16种Pristiograptus的亚种。提出了五个新的亚种P. dubius magnus，P。dubius paezerensis，P。dubius praelodenicensis，P。dubius postfrequens和P. dubius postmagnus。

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