An armoured Cambrian lobopodian from China with arthropod-like appendages
An armoured Cambrian lobopodian from China with arthropod-like appendages
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来自中国的一种装甲寒武纪叶足类动物，具有类似节肢动物的附肢
DOI：
10.1038/nature09704
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发表时间：
2011-02-24
期刊：
影响因子：
64.8
通讯作者：
Zhang, Xingliang
中科院分区：
文献类型：
--
作者：
Liu, Jianni;Steiner, Michael;Zhang, Xingliang
保存软体生物的寒武纪化石Lagerstatten对我们理解后生动物起源有很大贡献（1-3）。深足纲动物是一个特别有趣的群体，它们在寒武纪海洋中多样化和繁盛。它们类似于“有腿的蠕虫”，长期以来一直引起人们的广泛关注，因为它们可能产生了Onychophora（天鹅绒蠕虫）（4-6）和Tardigrada（水熊）（7,8），以及一般的节肢动物（9-12）。本文将Diania actiformis gen. et sp. 11描述为来自中国西南云南澄江化石lagerstate（寒武纪第三期）的“甲”足类动物。尽管与其他典型的足叶动物有相同的特征，但它的特点是拥有强壮的、可能是硬化的附属物，附属物似乎是铰接式的。就肢体形态而言，据我们所知，它比迄今为止记录的任何足类动物都更接近节肢动物的状态。系统发育分析显示其处于派生位置，接近节肢动物；因此，它似乎属于接近成为真正节肢动物的组织等级。此外，D. cactiformis可能暗示关节化（四肢硬化化）先于关节化（身体硬化化）。将我们的化石与其他叶足动物附属物形态进行比较——见Kerygmachela(9,10), Jianshanopodia（13）和Megadictyon（12）——加强了这个群体作为一个整体是副肢动物的假设，不同的分类群表达不同等级的节肢动物。
Cambrian fossil Lagerstatten preserving soft-bodied organisms have contributed much towards our understanding of metazoan origins(1-3). Lobopodians are a particularly interesting group that diversified and flourished in the Cambrian seas. Resembling 'worms with legs', they have long attracted much attention in that they may have given rise to both Onychophora (velvet worms)(4-6) and Tardigrada (water bears)(7,8), as well as to arthropods in general(9-12). Here we describe Diania cactiformis gen. et sp. nov. as an 'armoured' lobopodian from the Chengjiang fossil Lagerstatte (Cambrian Stage 3), Yunnan, southwestern China. Although sharing features with other typical lobopodians, it is remarkable for possessing robust and probably sclerotized appendages, with what appear to be articulated elements. In terms of limb morphology it is therefore closer to the arthropod condition, to our knowledge, than any lobopodian recorded until now. Phylogenetic analysis recovers it in a derived position, close to Arthropoda; thus, it seems to belong to a grade of organization close to the point of becoming a true arthropod. Further, D. cactiformis could imply that arthropodization (sclerotization of the limbs) preceded arthrodization (sclerotization of the body). Comparing our fossils with other lobopodian appendage morphologies-see Kerygmachela(9,10), Jianshanopodia(13) and Megadictyon(12)-reinforces the hypothesis that the group as a whole is paraphyletic, with different taxa expressing different grades of arthropodization.