Hyoliths with pedicles illuminate the origin of the brachiopod body plan
Hyoliths with pedicles illuminate the origin of the brachiopod body plan
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带蒂的Hyoliths阐明了腕足动物身体结构的起源
DOI：
10.1098/rspb.2018.1780
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发表时间：
2018-09-26
影响因子：
4.7
通讯作者：
Zhu, Maoyan
中科院分区：
文献类型：
--
作者：
Sun, Haijing;Smith, Martin R.;Zhu, Maoyan
在寒武纪时期出现的第一批壳化石中，有一群古生代的舌轮动物在分类学上存在问题。基于其独特的外骨骼，舌骨在历史上被划分为一个独立的门，可能与软体动物，星虫或lophophorates密切相关，但其精确的系统发育位置仍然不确定。本文描述了澄江湖寒武系第二统第三期的一个新的直孢类透明体Pedunculotheca diania Sun，Zhao et Zhu gen. et sp. nov.，其具有非矿化的附着结构，与腕足动物的蒂非常相似--这是在舌骨中首次报道的蒂器官。这个器官建立了一个无柄的，悬浮液喂养生态这些orthothecides和其他特征（例如，双边对称的双壳壳包围过滤室和分化的主要领域）-确定舌骨干组腕足动物。我们的系统发育分析表明，舌骨和冠腕足动物来自一个tommotiid级，和蒂有一个单一的起源内的腕足动物总组。
Hyoliths are a taxonomically problematic group of Palaeozoic lophotrochozoans that are among the first shelly fossils to appear in the Cambrian period. On the basis of their distinctive exoskeleton, hyoliths have historically been classified as a separate phylum with possible affinities to the molluscs, sipunculans or lophophorates—but their precise phylogenetic position remains uncertain. Here, we describe a new orthothecide hyolith from the Chengjiang Lagerstätte (Cambrian Series 2 Stage 3), Pedunculotheca diania Sun, Zhao et Zhu gen. et sp. nov., which exhibits a non-mineralized attachment structure that strikingly resembles the brachiopod pedicle—the first report of a peduncular organ in hyoliths. This organ establishes a sessile, suspension feeding ecology for these orthothecides and—together with other characteristics (e.g. bilaterally symmetrical bivalve shell enclosing a filtration chamber and the differentiation of cardinal areas)—identifies hyoliths as stem-group brachiopods. Our phylogenetic analysis indicates that both hyoliths and crown brachiopods derived from a tommotiid grade, and that the pedicle has a single origin within the brachiopod total group.