LEPERDITICOPID ARTHROPODS (ORDOVICIAN-LATE DEVONIAN): FUNCTIONAL MORPHOLOGY AND ECOLOGICAL RANGE
LEPERDITICOPID ARTHROPODS (ORDOVICIAN-LATE DEVONIAN): FUNCTIONAL MORPHOLOGY AND ECOLOGICAL RANGE
复制标题
鳞甲节肢动物（奥陶纪-晚泥盆纪）：功能形态和生态范围
作者：
J. Vannier;Shang;M. Coen
本文根据中国泥盆纪保存较好的标本，并与现代介形类进行了详细的比较，分析了奥陶纪-泥盆系最上部的麻风类节肢动物的功能形态学和个体生态学。Leperditicopids是大型的双瓣节肢动物（成虫体长约5至50毫米），通常有不对称的甲壳（强烈的腹侧重叠），一个复杂的肌肉系统（有力的内收肌、外在肌、腱结构），其附着物作为疤痕保存在外骨骼和斯坦科恩的内表面上，和广泛的辐射状的皮肤窦网络，可能参与气体和离子交换（氧的摄取和运输，呼吸调节）。内收肌瘢痕附近的明显人字形瘢痕被解释为下颌腱性结构的锚定点，可能参与瓣膜的打开机制。甲壳的超微结构是可比的厚壳最近myodocopid介形虫。对麻风科动物出现情况（沉积环境、相关动物群和植物群）的回顾表明，该种群优先占据受到环境压力（盐度、温度、湿度）的非常浅的边缘栖息地（潮滩、礁滩、泻湖、海湾或河口复合体）。这一生态范围意味着特定的适应性（干旱调节，抗干燥），并得到形态学证据的支持（例如，循环系统，甲壳封闭系统，厚壳）。大多数麻风类有底栖生活方式，可能是碎屑饲料。它们可能已经适应了（强大的下颚）在藻类/微生物垫上刮食物。其典型的发生模式（单特异性，大量丰度）显示了机会种群的一些特征（例如，最近介形类，鳃足类）生活在多变的环境中。与介形类的形态相似性很重要（例如，肌肉和腱的特征，循环系统，瓣膜重叠，甲壳超微结构），但由于缺乏来自软体部分的证据，与该组的分类关系仍然没有定论。
Abstract The functional morphology and autecology of leperditicopid arthropods (Ordovician-uppermost Devonian) are analyzed in the light of well-preserved specimens from the Devonian of China and detailed comparisons with recent ostracodes. Leperditicopids were large, bivalved arthropods (adults ranging from 5 to about 50 mm in length) typically with an asymmetric carapace (strong ventral overlap), a complex muscular system (powerful adductors, extrinsic muscles, tendinous structures) whose insertions are preserved as scars on the inner surface of the exoskeleton and steinkerns, and an extensive radiating network of integumental sinuses probably involved in gaseous and ionic exchanges (oxygen uptake and transport, osmoregulation). The conspicuous chevron scars adjacent to the adductor scars are interpreted as the anchoring spots of mandibular tendinous structures possibly involved in the opening mechanism of the valves. The ultrastructure of the carapace is comparable to that of thick-shelled recent myodocopid ostracodes. A review of leperditicopid occurences (depositional environment, associated faunas and floras) shows that the group preferentially occupied very shallow marginal habitats (tidal flats, reef-flats, lagoons, embayments, or estuarian complexes) that were subjected to environmental stress (salinity, temperature, moisture). This ecological range implies specific adaptations (osmoregulation, resistance to desiccation) supported by morphological evidence (e.g., circulatory system, carapace closing system, thick shell). Most leperditicopids had epibenthic lifestyles and were probably detritus feeders. They may have been adapted (powerful mandibles) to scrape food on algal/microbial mats. Their typical pattern of occurrence (monospecificity, large numerical abundance) displays some of the characteristics of opportunistic populations (e.g., recent ostracodes, branchiopods) living in variable environments. Morphological similarities with Ostracoda are important (e.g., muscular and tendinous features, circulatory system, valve overlap, carapace ultrastructure) but taxonomic relationships with that group remain inconclusive because of the lack of evidence from soft parts.