Paleolimulids represent a group of fossil horseshoe crabs that are morphologically comparable to the extant limulids. Recent work has highlighted that, contrary to traditional opinions, Paleolimulidae has a limited taxonomic and morphological diversity at the species and generic level. In the light of this new perspective, it is imperative that material documenting novel facets of species within this Paleozoic group be explored. Here, we revisit Paleolimulus kunguricus Naugolnykh, 2017 from the Cisuralian of Russia and illustrate distinct ontogenetic stages of the species. The so-called ‘trilobite’ stage, two juveniles and adult stages are presented. We document morphological transitions within the prosomal and opisthosomal sections, and changes to the lateral compound eye position. These shifts may reflect distinct life modes experienced during ontogeny. Documentation of Selenichnites ichnofossils associated with P. kunguricus specimens present insight into how the xiphosurid functioned during the later ontogenetic stages and illustrate the first evidence for shell-crushing in fossil xiphosurids. Finally, we demonstrate how occupation of lagoonal palaeoenvironments limited competition with other organisms and aided the survival of Xiphosurida.

中文翻译：

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Paleolimulus kunguricus 的生态学、形态学和个体发育——一种来自俄罗斯独联体-乌拉尔地区昆古尔（Cisuralian）的鲎

古鲎科动物代表一组在形态上与现存鲎科动物相似的化石鲎。最近的工作强调，与传统观点相反，Paleolimulidae 在物种和属水平上的分类和形态多样性有限。鉴于这一新观点，必须探索记录该古生代物种新方面的材料。在这里，我们重温古鲎 kunguricusNaugolnykh，2017 年来自俄罗斯的 Cisuralian，展示了该物种不同的个体发育阶段。所谓的“三叶虫”阶段，有两个少年阶段和成年阶段。我们记录了前体和后体部分的形态学转变，以及侧复眼位置的变化。这些转变可能反映了个体发育过程中经历的不同生活模式。与P. kunguricus标本相关的Selenichnites ichnofossils的文献提供了对 xiphosurid 在后期个体发育阶段如何发挥作用的见解，并说明了化石 xiphosurids 壳破碎的第一个证据。最后，我们展示了对泻湖古环境的占领如何限制了与其他生物的竞争并帮助了 Xiphosurida 的生存。