Discovery of Jurassic Conchostracans with Well-Preserved Soft Parts and Notes on Its Biological Significance
Discovery of Jurassic Conchostracans with Well-Preserved Soft Parts and Notes on Its Biological Significance
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DOI：
10.1007/978-3-662-12662-2_14
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发表时间：
1990
期刊：
影响因子：
2.6
通讯作者：
Wentang Zhang;Yanbin Shen;Shaowu Niu
中科院分区：
文献类型：
--
作者：
Wentang Zhang;Yanbin Shen;Shaowu Niu
冀北滦平周营子中侏罗世九龙山组发现了软体部分保存完好的甲壳类化石。藏品中保存的四种类型的图案分别为甲壳瓣、带软体的甲壳瓣、单独的软体部分和幼虫后。头骨、下颌骨、触角、羽状刚毛、夹子、卵、附属物、消化管、尾节和尾部毛囊清晰可见。所有标本均被认为是一新种，新种--六平裸甲属。与现存的漏斗类相比，该新种应命名为脊尾亚目。考虑到活体和化石材料在头骨和端骨上的相似性，新种可能代表了水母科生物的一种祖先形式。在对活的和化石的甲壳类进行较高分类的研究之后，本文提出了一个统一的分类方案，包括3个目：Laeviscaudata Linder，1945，Spinicaudata Linder，1945和Leaiina Kobayashi，1972。根据沉积特征，小高岭石和伴生昆虫的出现，侏罗纪甲壳类生活的水域似乎是一个小而安静的浅水塘。它可能已经存在了至少一个月或更长时间，新物种可以世代繁殖。此外，水域中没有肉食性和腐食性动物。
Conchostracans with well-preserved soft parts were found from the Middle Jurassic Jiulongshan formation at Zhouyingzi of Luanping, northern Hebei. Four types of preserved patterns in the collections show the carapace valve, carapace valve with soft parts, soft parts alone and post-larvae respectively. The cephalon, mandibula, antennae, pinnate setae, claspers, eggs, appendages, digestive tube, caudal segment (telson) and caudal furca are clearly visible. All the specimens are considered to represent a new species,Euestheria luanpingensissp. nov., which occurs in association with fossil insects and plant remains.As compared with living concostracans, the new species should be referred to the suborder Spinicaudata. In consideration of the similarities in the cephalon and telson between the living and fossil materials, it is possible that the new species represents an ancestral form of living family Cyzicidae.Following the study of the higher classification for the living and fossil conchostracans, a unified scheme proposed here comprises 3 orders: Laeviscaudata Linder, 1945; Spinicaudata Linder, 1945; and Leaiina Kobayashi, 1972.Based on the sedimentary characters, the occurrence of minor kaolinite and the associated insects, the waters in which the conchostracans lived seemed to be a small, shallow and quiet pond in the Jurassic time. It might have existed for at least one month or more, and the new species could reproduce from generation to generation. Besides, in the waters there were no carnivorous and saprophagous animals.