论文标题：A Cambrian unarmoured lobopodian, †Lenisambulatrix humboldti gen. et sp. nov., compared with new material of †Diania cactiformis
期刊：
作者：Qiang Ou & Georg Mayer
发表时间：2018/09/20
数字识别码：10.1038/s41598-018-31499-y
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《明升体育app手机版》近日发表的一项研究A Cambrian unarmoured lobopodian, †Lenisambulatrix humboldti gen. et sp. nov., compared with new material of †Diania cactiformis描述了寒武纪（5.41-4.85亿年前）叶足动物的一个新物种——一种具有柔软附肢的蠕虫状动物。
明升官网地质大学（北京）的欧强和德国卡塞尔大学的Georg Mayer将这个命名为Lenisambulatrix humboldti的新物种与之前描述过的叶足动物仙掌滇虫（Diania cactiformis）进行比较，发现了一些新细节。
图1：Lenisambulatrix humboldti的三维重建模型。图源：Ou & Mayer
作者指出，两种叶足动物的身形和躯体分节都很相似，都有较厚较长的附肢（叶足），长度约为11.6-18mm。与其它叶足动物不同的是，两个物种似乎都无爪。不过，仙掌滇虫的躯干表面布满刺状铠甲，故其绰号为“行走的仙人掌”，但L. humboldti的整个躯体似乎并无盔甲。
图2：Lenisambulatrix humboldti 的正模标本。图源：Ou & Mayer
根据作者描述，新物种的躯体有分节、呈管状，与蠕虫类似，且每个体节都有一对附肢。新物种躯体只有一端得以保存，且并未发现如眼睛、嘴巴或触须这些可以确定此端为头部的显著特征。相比之下，假定为仙掌滇虫头部的部位则具有明显的类似头盔的结构。
图3：叶足动物仙掌滇虫的细节图。图源：Ou & Mayer
从两个物种的形态特征可以大致判断出它们曾经可能的生活方式。因为两者都是海洋栖息动物，它们的无爪附肢可能是为了适应在柔软的海底行走或爬行。仙掌滇虫的厚重铠甲可能有助于防御捕食者的攻击，而L. humboldti的躯体较柔软，或表明其个体曾过着隐居生活，藏于缝隙或海绵群体中以抵御被捕食的风险。
摘要：Cambrian marine lobopodians are generally considered as predecessors of modern panarthropods (onychophorans, tardigrades, and arthropods). Hence, further study of their morphological diversity and early radiation may enhance our understanding of the ground pattern and evolutionary history of panarthropods. Here, we report a rare lobopodian species, †Lenisambulatrix humboldti gen. et sp. nov. (“Humboldt lobopodian”), from the early Cambrian Chengjiang Lagerstätte and describe new morphological features of †Diania cactiformis, a coeval armoured lobopodian nicknamed “walking cactus”. Both lobopodian species were similar in possessing rather thick, elongate lobopods without terminal claws. However, in contrast to †Diania cactiformis, the body of which was heavily armored with spines, the trunk and limbs of the Humboldt lobopodian were entirely unarmored. Our study augments the morphological diversity of Cambrian lobopodians and presents two evolutionary extremes of cuticular ornamentation: one represented by the Humboldt lobopodian, which was most likely entirely “naked”, the other epitomized by †D. cactiformis, which was highly “armoured”.
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