Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada
Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada
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DOI：
10.4202/app.2009.0024
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发表时间：
2009-12-01
影响因子：
1.8
通讯作者：
Collins, Desmond
中科院分区：
文献类型：
--
作者：
Garcia-Bellido, Diego C.;Vannier, Jean;Collins, Desmond
来自中寒武世Burgess页岩的40多个标本揭示了Isoxys的详细解剖结构，Isoxys是一种世界性分布的双瓣节肢动物，在这里以两个物种为代表，即Isoxys acutangulus和Isoxys longissimus。I. acutangulus有一个非矿化的头盾，侧面胸膜褶皱（=以前作者的“瓣膜”）几乎完全覆盖了动物的身体，大的球形眼睛和一对单枝的无脊椎附属物，沿着它们的前缘有坚固的多刺的生长物。以下13个附属物具有统一的双枝设计，即，短的内足动物和桨状的外足动物，边缘有刚毛，可能有游泳的功能。躯干的末端有一个襟翼状的尾索，突出在头罩的后缘之外。我的肠子。Acutangulus是管状的，从嘴到尾，两侧有许多3D保存的球状配对特征，被解释为消化腺。I. acutangulus表明这种动物是一种游泳者，也是一种生活在海底的视觉捕食者。Isoxys longissimus的一般解剖结构与L acutangulus相似，但关于其附属物和视觉器官的确切形状的信息较少。I.最长肌的特征是前后棘极长。目前已知有七种Isoxys物种的软体部分保存完好，I。尖丘岛longissimus，I. auritus和I. curvirostratus，I. communis和I. glaessneri和I.来自格陵兰的天狼星帕塞特的volucris。Isoxys的前附肢与其他寒武纪节肢动物的前附肢非常相似，其特征是一对“大附肢”，具有共同的抓握功能，但长度和形状存在一些变化。
More than forty specimens from the middle Cambrian Burgess Shale reveal the detailed anatomy of Isoxys, a worldwide distributed bivalved arthropod represented here by two species, namely Isoxys acutangulus and Isoxys longissimus. I. acutangulus had a non-mineralized headshield with lateral pleural folds (= "valves" of previous authors) that covered the animal's body almost entirely, large frontal spherical eyes and a pair of uniramous prehensile appendages bearing stout spiny outgrowths along their anterior margins. The 13 following appendages had a uniform biramous design-i.e., a short endopod and a paddle-like exopod fringed with marginal setae with a probable natatory function. The trunk ended with a flap-like telson that protruded beyond the posterior margin of the headshield. The gut of I. acutangulus was tube-like, running from mouth to telson, and was flanked with numerous 3D-preserved bulbous, paired features interpreted as digestive glands. The appendage design of I. acutangulus indicates that the animal was a swimmer and a Visual predator living off-bottom. The general anatomy of Isoxys longissimus was similar to that of L acutangulus although less information is available on the exact shape of its appendages and visual organs. I. longissimus is characterized by extremely long anterior and posterior spines. There are now seven Isoxys species known with soft-part preservation, I. acutangulus, I. longissimus from the Burgess Shale, I. auritus and I. curvirostratus from the Maotianshan Shale of China, I. communis and I. glaessneri from the EMU Bay Shale of Australia and I. volucris from Sirius Passet in Greenland. The frontal appendages of Isoxys strongly resemble those of other Cambrian arthropods, characterized by a single pair of "great appendages" with a shared prehensile function yet some variability in length and shape.