Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus.
Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus.
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DOI：
10.1038/srep32817
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发表时间：
2016-09-06
影响因子：
4.6
通讯作者：
Sansom RS
中科院分区：
文献类型：
--
作者：
Sansom RS
异常保存的寒武纪化石记录为动物的早期进化史提供了独特的见解。特殊的软组织保存机制的理解框架的动物群及其进化意义的所有解释。这是特别真实的化石蜕皮动物保存神经组织的最新解释。然而，软组织保存的模型缺乏来自现实研究的经验支持。在这里，实验衰减的priapulid Priapulus揭示一致的偏见，迅速丧失内部非表皮解剖结构相比，adrenocitrant表皮解剖结构。这与伯吉斯页岩类型保存的模型一致，并表明内部组织如果有机保存，则不太可能保持保真度。这种模式，沿着与极端的身体边缘扭曲，是一致的onychophoran腐烂，因此解决了一般的早期蜕皮动物。应用这些模式的系统发育数据发现scalidophoran类群是非常敏感的taphonomically知情的字符编码，但不是panarthropodan类群。Priapulid衰变也有意想不到的相关性的解释肌节在化石脊索动物。衰变数据不仅作为保存模型的测试，但也解释蜕皮动物化石解剖学的框架，以及随后的进化推断。
The exceptionally preserved Cambrian fossil record provides unique insight into the early evolutionary history of animals. Understanding of the mechanisms of exceptional soft tissue preservation frames all interpretations of the fauna and its evolutionary significance. This is especially true for recent interpretations of preserved nervous tissues in fossil ecdysozoans. However, models of soft tissue preservation lack empirical support from actualistic studies. Here experimental decay of the priapulid Priapulus reveal consistent bias towards rapid loss of internal non-cuticular anatomy compared with recalcitrant cuticular anatomy. This is consistent with models of Burgess Shale-type preservation and indicates that internal tissues are unlikely to be preserved with fidelity if organically preserved. This pattern, along with extreme body margin distortion, is consistent with onychophoran decay, and is therefore resolved as general for early ecdysozoans. Application of these patterns to phylogenetic data finds scalidophoran taxa to be very sensitive to taphonomically informed character coding, but not panarthropodan taxa. Priapulid decay also have unexpected relevance for interpretation of myomeres in fossil chordates. The decay data presented serve not only as a test of models of preservation but also a framework with which to interpret ecdysozoan fossil anatomies, and the subsequent evolutionary inferences drawn from them.