Ontogeny and microstructure of the enigmatic Cambrian tommotiid Sunnaginia Missarzhevsky, 1969
Ontogeny and microstructure of the enigmatic Cambrian tommotiid Sunnaginia Missarzhevsky, 1969
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神秘的寒武纪 tommotiid Sunnaginia Missarzhevsky 的个体发育和微观结构，1969
DOI：
10.1111/j.1475-4983.2012.01131.x
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发表时间：
2012
期刊：
影响因子：
2.6
通讯作者：
F. Marone
中科院分区：
文献类型：
--
作者：
D. Murdock;P. Donoghue;S. Bengtson;F. Marone
翻译后摘要：tommotiids是一个重要的组成部分，最早的骨骼动物仍然在化石记录中，大量发生在下寒武统。 Tommotiid属Sunnaginia的骨片被认为是腕足动物体平面进化假说的组成部分，其形态介于管状Eccentrocotheca的非特化骨片和tannuolinids的特化骨片之间。丰富的Sunnaginia？从英国什罗普郡下寒武统的ComleyLimestone（3-4阶）中回收了具有宽的个体发育谱的覆瓦状骨片，并与来自西伯利亚AldanRiver（Tommotian最上部）的Sunnaginiaimbricata进行了比较。新的显微结构数据，收集使用同步辐射X射线断层扫描显微镜，揭示了一个独特的微观结构Sunnaginia？层间空腔由一系列连续的支柱跨越，给人一种柱廊的外观形成对比的S。覆瓦状。这些数据驳斥了包括在Sunnaginiidae的偏心鞘，并强调需要修订的超属分类的tommotiids。相反，Sunnaginia sclerites和那些tannuolinids之间的结构相似性表明了这个群体的密切关系。最近的系统发育假说将tannuolinids视为茎舌形腕足动物，与Paterimitra加上Paterinid（可能是rhynchonelliform）腕足动物作为它们的姐妹群。因此，我们的新数据将Sunnaginia解析为接近定义冠-腕足类的节点。然而，支持这种系统发育方案的字符不能始终适用于所有类群，也没有定义一系列嵌套分支。因此，我们建议，一个更彻底的系统发育分析是必要的，根据这里提供的数据和其他最近的描述。
Abstract: The tommotiids are a significant component of the earliest skeletal animal remains in the fossil record, occurring in large numbers in the Lower Cambrian. Sclerites of the tommotiid genus Sunnaginia have been implicated as integral to hypotheses regarding the evolution of the brachiopod body plan, with a morphology intermediate between the unspecialized sclerites of the tubular Eccentrotheca and the specialized sclerites of the tannuolinids. Abundant Sunnaginia ?imbricata sclerites, of a broad ontogenetic spectrum, were recovered from the Comley Limestone, Lower Cambrian (Stages 3–4), Shropshire, UK and compared to Sunnaginia imbricata from the Aldan River, Siberia (uppermost Tommotian). New microstructural data, collected using synchrotron radiation X‐ray tomographic microscopy, reveal a unique microstructure for Sunnaginia ?imbricata sclerites among the tommotiids; interlamellar cavities spanned by a series of continuous pillars, giving a colonnaded appearance contrasting to that of S. imbricata. These data refute the inclusion of Eccentrotheca within the Sunnaginiidae and highlight the need for a revision of suprageneric classification of the tommotiids. Rather, structural similarities between Sunnaginia sclerites and those of the tannuolinids suggest a close affinity to this group. Recent phylogenetic hypotheses place the tannuolinids as stem‐linguliform brachiopods, with Paterimitra plus the paterinid (and possibly rhynchonelliform) brachiopods as their sister group. Our new data therefore resolve Sunnaginia as close to the node defining crown‐Brachiopoda. However, the characters supporting this phylogenetic scheme cannot be consistently applied to all taxa, nor do they define a series of nested clades. We therefore suggest that a more thorough phylogenetic analysis is required in the light of the data presented here and other recent descriptions.
影响因子：
2.7
作者：
Harvey, Thomas H. P.;Williams, Mark;Gabbott, Sarah E.
通讯作者：
Gabbott, Sarah E.