Crinoid calyx origin from stem radial echinoderms
Crinoid calyx origin from stem radial echinoderms
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海百合花萼起源于茎放射状棘皮动物
DOI：
10.1017/jpa.2023.14
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发表时间：
2023
影响因子：
1.4
通讯作者：
Mongiardino Koch, Nicolás
中科院分区：
文献类型：
--
作者：
Guensburg, Thomas E.;Mooi, Rich;Mongiardino Koch, Nicolás
来自已知最早的海百合（Tremadocian，早奥陶纪）的证据，被称为原海百合，被用来假设花萼元素进化的初始步骤。原海百合花萼由轴外的初生板和周围的次生板组成（两者都有沿着缝合线的表皮），这与那些更冠状的化石和现存的海百合不同，后者的花萼板组织得很强。这些减少启发了几个计划，其中命名板在这些花萼。然而，在原海百合中看到的初级-次级系统首先出现在寒武纪茎放射状棘皮动物中，初级毛代表中心，在个体发育过程中依次添加次级毛。因此，原海百合花萼代表了最早的棘皮动物和冠状海百合之间的中间状态。位置和个体发育表明，某些初级的损失仍然发生的次生，导致邻接的初级到联合交替圆海百合的特点。这种转变性事件包括抑制继发性植板和修饰，或者更常见的是消除呼吸结构。这些数据表明，subradial萼板术语不符合最常见的用法，而是支持这些传统表达的另一种重新定义。在最早的海百合中，在花萼个体发育过程中，固定射线的延伸和口侧生长先于连体的初级毛。限制与修改或消除花萼呼吸结构也伴随着这种修改。系统发育分析强烈支持海百合起源于早期的五射棘皮动物，独立于芽生动物。因此，所有Tremadocian海百合表达了一个独特的聚合体的近形和近形的共性;所有分支内的海百合分支早期，从传统的子类级分支。然而，在这个组合中的每个分类群表示至少一个诊断的camerate，枝，或pandroid分支的形态学。
Evidence from the earliest-known crinoids (Tremadocian, Early Ordovician), called protocrinoids, is used to hypothesize initial steps by which elements of the calyx evolved. Protocrinoid calyces are composed of extraxial primary and surrounding secondary plates (both of which have epispires along their sutures) that are unlike those of more crownward fossil and extant crinoids in which equivalent calycinal plating is strongly organized. These reductions inspired several schemes by which to name the plates in these calyces. However, the primary-secondary systems seen in protocrinoids first appeared among Cambrian stem radial echinoderms, with primaries representing centers around which secondaries were sequentially added during ontogeny. Therefore, the protocrinoid calyx represents an intermediate condition between earliest echinoderms and crownward crinoids. Position and ontogeny indicate certain primaries remained as loss of secondaries occurred, resulting in abutting of primaries into the conjoined alternating circlets characteristic of crinoids. This transformative event included suppression of secondary plating and modification or, more commonly, elimination of respiratory structures. These data indicate subradial calyx plate terminology does not correspond with most common usage, but rather, supports an alternative redefinition of these traditional expressions. Extension and adoral growth of fixed rays during calyx ontogeny preceded conjoined primaries in earliest crinoids. Restriction with modification or elimination of calyx respiratory structures also accompanied this modification. Phylogenetic analyses strongly support crinoid origination from early pentaradiate echinoderms, separate from blastozoans. Accordingly, all Tremadocian crinoids express a distinctive aggregate of plesiomorphic and apomorphic commonalities; all branch early within the crinoid clade, separate from traditional subclass-level clades. Nevertheless, each taxon within this assemblage expresses at least one diagnostic apomorphy of camerate, cladid, or disparid clades.
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DOI：
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