A quantitative assessment of ontogeny and molting in a Cambrian radiodont and the evolution of arthropod development

IF 2.6 2区 地球科学 Q2 BIODIVERSITY CONSERVATION
Paleobiology Pub Date : 2023-08-11 DOI:10.1017/pab.2023.18
J. Moysiuk, Jean‐Bernard Caron
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引用次数: 1

Abstract

Radiodonta is a clade of stem euarthropods of central importance to our understanding of the evolution of this phylum. Radiodonts include some of the largest early Paleozoic animals; however, little is known about their ontogeny. We present an analysis of molting patterns and ontogeny in the radiodont Stanleycaris based on 265 exceptionally preserved specimens from the mid-Cambrian (Wuliuan) Burgess Shale. Ranging in size from 10 to 83 mm, they constitute the most extensive radiodont ontogenetic series known. Using a novel morphospace approach, we show that putative carcasses and exuviae can be quantitatively distinguished by the particular suites of structures preserved and their modes of preservation. We propose that Stanleycaris, and probably other radiodonts, molted via a suture near the anterior of the trunk. Similar anterior molting strategies, with a suture located at the head–trunk boundary, are shared with some Cambrian euarthropods and are potentially ancestral. Allometric analyses suggest that as Stanleycaris body size increased, the head sclerite and neck became relatively broader, while the trunk and flaps became slightly longer. The eyes developed precociously, indicating an important role of visual processing in juveniles. Finally, we find evidence for an initial anamorphic developmental phase, where segment number increased at least from 11 or 12 up to 17, followed by an epimorphic phase, in which growth continued without segment addition. This is consistent with the hypothesis that finite postembryonic segment addition (hemianamorphosis) is ancestral for arthropods and refines the timing of the origin of this important developmental mode.
寒武纪放射虫个体发生和蜕皮的定量评估及节肢动物发育的进化
放射齿兽是茎真节肢动物的一个分支,对我们了解这一门的进化至关重要。放射性动物包括一些最大的早期古生代动物;然而,人们对它们的个体发生知之甚少。本文以中寒武纪(武流)伯吉斯页岩中保存的265个特殊标本为基础,分析了放射性Stanleycaris的蜕皮模式和个体发育。它们的大小从10毫米到83毫米不等,构成了已知的最广泛的放射成因系列。使用一种新颖的形态空间方法,我们表明假定的尸体和蜕皮可以通过保存的特定结构套件和它们的保存模式来定量区分。我们认为Stanleycaris,可能还有其他放射兽,是通过躯干前部附近的缝合线脱皮的。一些寒武纪真节肢动物也有类似的前蜕皮策略,在头干边界处有一条缝线,可能是它们的祖先。异速生长分析表明,随着Stanleycaris体型的增大,头部硬骨和颈部变得相对更宽,而躯干和襟翼则略微变长。眼睛发育较早,表明在青少年中视觉处理起着重要作用。最后,我们发现了最初的变形发育阶段的证据,其中节数至少从11或12增加到17,然后是附形阶段,在这个阶段,生长继续,没有增加节。这与有限胚胎后节段添加(半变形)是节肢动物祖先的假设一致,并完善了这一重要发育模式起源的时间。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Paleobiology
Paleobiology 地学-古生物学
CiteScore
5.30
自引率
3.70%
发文量
38
审稿时长
>12 weeks
期刊介绍: Paleobiology publishes original contributions of any length (but normally 10-50 manuscript pages) dealing with any aspect of biological paleontology. Emphasis is placed on biological or paleobiological processes and patterns, including macroevolution, extinction, diversification, speciation, functional morphology, bio-geography, phylogeny, paleoecology, molecular paleontology, taphonomy, natural selection and patterns of variation, abundance, and distribution in space and time, among others. Taxonomic papers are welcome if they have significant and broad applications. Papers concerning research on recent organisms and systems are appropriate if they are of particular interest to paleontologists. Papers should typically interest readers from more than one specialty. Proposals for symposium volumes should be discussed in advance with the editors.
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