Spine-like structures in Paleogene muricate planktonic foraminifera
Spine-like structures in Paleogene muricate planktonic foraminifera
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DOI：
10.5194/jm-41-107-2022
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发表时间：
2022-08
影响因子：
2
通讯作者：
P. Pearson;E. John;B. Wade;S. D’haenens;C. Lear
中科院分区：
文献类型：
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作者：
P. Pearson;E. John;B. Wade;S. D’haenens;C. Lear
抽象。在古近纪海洋中，纹状复孔有孔虫是一个种类丰富的已灭绝分支，作为海洋上层的地球化学代用载体，被广泛应用于古气候研究。其特征壁纹理具有被称为“muricae”的表面突起，该突起由测试壁的连续层的向上偏转和隆起形成。一般认为该组缺乏“真正的刺”：即针状方解石晶体嵌入和突出的测试表面，如出现在许多现代和一些古近纪组。在这里，我们提出的证据，从抛光部分，表面壁扫描电子显微镜图像和测试解剖，显示径向取向的结晶刺状结构发生在中心的muricae在不同种类的蜱螨亚纲和Morozovella和预测从测试壁的生活。它们的形态和在壁中的位置表明它们独立于真正的刺进化。尽管如此，它们可能具有与现代物种中的刺相似的功能，包括帮助浮力和捕食，特别是窝藏藻类光合共生体，我们认为它们可能首先进化的功能。我们的观察加强了古近纪混合层居住的浮游有孔虫和现代的棘状有孔虫之间的相似性。
Abstract. Muricate planktonic foraminifera comprise an extinct clade that was diverse and abundant in the Paleogene oceans and are widely used in palaeoclimate research as geochemical proxy carriers for the upper oceans. Their characteristic wall texture has surface projections called “muricae” formed by upward deflection and mounding of successive layers of the test wall. The group is generally considered to have lacked “true spines”: that is, acicular calcite crystals embedded in and projecting from the test surface such as occur in many modern and some Paleogene groups. Here we present evidence from polished sections, surface wall scanning electron microscope images and test dissections, showing that radially orientated crystalline spine-like structures occur in the centre of muricae in various species of Acarinina and Morozovella and projected from the test wall in life. Their morphology and placement in the wall suggest that they evolved independently of true spines. Nevertheless, they may have served a similar range of functions as spines in modern species, including aiding buoyancy and predation and especially harbouring algal photosymbionts, the function for which we suggest they probably first evolved. Our observations strengthen the analogy between Paleogene mixed-layer-dwelling planktonic foraminifera and their modern spinose counterparts.