Abstract

Clam shrimps constitute a paraphyletic group of bivalved branchiopod crustaceans that includes orders Laevicaudata, Spinicaudata, and Cyclestherida. The unique mineral content of the carapace, formed by molt retention in Spinicaudata and Cyclestherida, has been variously ascribed to calcium carbonate or calcium phosphate. We analyzed the composition of modern carapaces from one laevicaudatan species, thirteen spinicaudatan species (including cyzicids, leptestheriids, and limnadiids), one cyclestherid species, and two species of the notostracan TriopsSchrank, 1803 (as an outgroup comparison within Branchiopoda) via Raman spectroscopy. The results were surprisingly variable. The outgroup Triops species varied in either having no mineral content to having a slight amount of calcium phosphate. The laevicaudatans likewise had a minor calcium phosphate peak; the leptestheriid spinicaudatan had strong calcium phosphate and calcium carbonate peaks; the limnadiid spinicaudatans were variable, varying from no mineral content to strong dual calcium carbonate and calcium phosphate peaks; the cyzicid spinicaudatans tended to have strong calcium phosphate peaks with some amount of calcium carbonate; and the cyclestherid had no mineral content. The results support the conclusion that spinicaudatans primitively have a dual mineralization system in their carapace that utilizes both calcium phosphate and calcium carbonate, with the calcium phosphate ability being basal. This suggestion of a dual mineralization system is novel in branchiopods and warrants study from material scientists. Better understanding of the distribution of phosphate versus carbonate among modern spinicaudatans will help us understand the evolution of biomineralization in the group. This, in turn, will shed light on the fossilization potential of different fossil clam-shrimp lineages.

中文翻译：

---

蛤虾甲壳成分的拉曼光谱分析（Branchiopoda：Laevicaudata，Spinicaudata，Cyclerstherida）：磷酸钙-碳酸钙双重成分

摘要

蛤虾是双壳类双足类甲壳动物的共生类群，其中包括orders（Laevicaudata），菠菜（Spinicaudata）和Cyclerstherida。甲壳中独特的矿物质含量是由菠菜和Cyclerstherida中的蜕皮保留所形成的，其归因于碳酸钙或磷酸钙。我们通过拉曼光谱分析了一种拉维卡达坦菌种，十三种多杀菌素菌种（包括cyzicids，leptestheriids和limnadiids），一种环孢菌素种和两种拉氏三叶虫Triops Schrank，1803年（作为Branchoiopoda的外群比较）的现代甲壳动物的组成。。结果令人惊讶地变化。外类群Triops种类不同，既无矿物质含量也有少量磷酸钙。Laevicaudatans同样具有较小的磷酸钙峰。瘦甾体梭菌素具有较强的磷酸钙和碳酸钙峰。limnadiid spinicaudatans是可变的，从无矿物质含量变化到碳酸钙和磷酸钙的双重强峰。杀孢子体梭菌素倾向于带有一些碳酸钙的强磷酸钙峰。并且该循环类固醇没有矿物质含量。结果支持这样的结论，即棘金刚tan最初在其甲壳中具有双重矿化系统，该系统利用磷酸钙和碳酸钙，而磷酸钙的能力是基础。关于双矿化系统的这一建议在分支足类中是新颖的，值得材料科学家进行研究。更好地了解磷酸盐的分布与现代棘金龙类中的碳酸盐相比，将有助于我们了解该群体中生物矿化的演变。反过来，这将揭示不同化石蛤虾谱系的化石潜力。