Developmental biology of the early Cambrian cnidarian Olivooides
Developmental biology of the early Cambrian cnidarian Olivooides
复制标题
早寒武世刺胞动物 Olivooides 的发育生物学
DOI：
10.1111/pala.12231
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发表时间：
2016-05-01
期刊：
影响因子：
2.6
通讯作者：
Donoghue, Philip C. J.
中科院分区：
文献类型：
--
作者：
Dong, Xi-Ping;Vargas, Kelly;Donoghue, Philip C. J.
化石胚胎提供了对灭绝生物发育模式的直接洞察，为基于比较胚胎学的发育进化假说提供了独特的检验。然而，这些化石只有在它们的胚胎学和系统发育亲缘关系受到很好的限制时才能有效地发挥这一作用。我们阐明和解释Olivoides从胚胎和成人阶段的发展，并使用这些数据来区分他们的解剖和亲和力的竞争解释。Olivooides的胚胎学主要特征是发育一个最初在外部形成，随后在内部形成，在孔处释放，促进胚胎直接发育成成年卵泡膜。内部解剖学仅从胚胎阶段开始，揭示了两个内部组织层，其中最内层发育成三个横向排列的壁，部分将管腔分为一个abapertural区域，解释为息肉的肠道，以及一个adapertural区域，包括类似于冠状钵水母的表皮齿的结构。Olivoides的解剖结构和发育模式与其他已知的橄榄状化石四角石属相似，四角石的不同之处在于其四面体对称，而不是五面体对称。我们拒绝以前的解释橄榄作为cycloneuralians，主要是因为他们缺乏一个通过肠道和内向，在胚胎和成人。相反，我们考虑了水母类刺胞动物之间橄榄形的亲和力;我们的系统发育分析支持他们的分类为总组冠，冠-Scyphozoa内。Olivooides和Quadrapyrgites的证据更广泛的生活史策略和bodyplan对称性，否则通常在现存的Scyphozoa特别是，刺胞动物更普遍的代表。
Fossilized embryos afford direct insight into the pattern of development in extinct organisms, providing unique tests of hypotheses of developmental evolution based in comparative embryology. However, these fossils can only be effective in this role if their embryology and phylogenetic affinities are well constrained. We elucidate and interpret the development of Olivooides from embryonic and adult stages and use these data to discriminate among competing interpretations of their anatomy and affinity. The embryology of Olivooides is principally characterized by the development of an ornamented periderm that initially forms externally and is subsequently formed internally, released at the aperture, facilitating the direct development of the embryo into an adult theca. Internal anatomy is known only from embryonic stages, revealing two internal tissue layers, the innermost of which is developed into three transversally arranged walls that partly divide the lumen into an abapertural region, interpreted as the gut of a polyp, and an adapertural region that includes structures that resemble the peridermal teeth of coronate scyphozoans. The anatomy and pattern of development exhibited by Olivooides appears common to the other known genus of olivooid, Quadrapyrgites, which differs in its tetraradial, as opposed to pentaradial symmetry. We reject previous interpretations of the olivooids as cycloneuralians, principally on the grounds that they lack a through gut and introvert, in embryo and adult. Instead we consider the affinities of the olivooids among medusozoan cnidarians; our phylogenetic analysis supports their classification as total‐group Coronata, within crown‐Scyphozoa. Olivooides and Quadrapyrgites evidence a broader range of life history strategies and bodyplan symmetry than is otherwise commonly represented in extant Scyphozoa specifically, and Cnidaria more generally.