State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China.
Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
PLoS One. 2023 Jun 7;18(6):e0282247. doi: 10.1371/journal.pone.0282247. eCollection 2023.
The enigmatic acid-resistant mesofossil genus Kuqaia is emended, a new species (Kuqaia scanicus) is instituted, and three established species are described from the Lower Jurassic (lower Pliensbachian) of the Kävlinge BH-928 core, in southern Sweden. Kuqaia has a distribution across the middle northern latitudes of Pangaea and is restricted to Lower to lower Middle Jurassic strata. Morphological characters support Kuqaia being the ephippia (resting egg/embryo cases) of Cladocera (Crustacea: Branchiopoda), and a probable early stem-group taxon of the Daphnia lineage. The paleoecology of the small planktonic crustaceans indicate purely fresh-water environments, such as lakes or ponds, all occurrences being in continental deposits, and the Kuqaia specimens possibly represent dry-season resting eggs. Chemical analyses of these and similar fossils, and of extant invertebrate eggs and egg cases are recommended to improve resolution of the biological affiliations of such mesofossil groups.
耐酸的神秘中间化石属库卡亚被修正，建立了一个新种（扫描库卡亚），并从瑞典南部的 Kävlinge BH-928 核心的下侏罗统（下普林尼安）描述了三个已确立的种。库卡亚分布在泛古陆的中北纬地区，仅限于下至中侏罗统地层。形态特征支持库卡亚是枝角类（甲壳纲：鳃足纲）的休眠卵/胚胎囊，并且可能是枝角类的早期谱系的原始分类单元。小型浮游甲壳动物的古生态学表明它们生活在纯粹的淡水环境中，如湖泊或池塘，所有的栖息地都是在大陆沉积物中，而库卡亚标本可能代表旱季的休眠卵。建议对这些和类似化石以及现存的无脊椎动物卵和卵囊进行化学分析，以提高对这些中间化石群生物亲缘关系的分辨率。
