中国科学院古脊椎动物与古人类研究所朱敏、英国布里斯托大学Philip C. J. Donoghue等研究人员合作揭示脊椎动物成对附属肢体的起源。该研究于2022年9月28日发表于国际一流学术期刊《自然》。
研究人员根据中国志留纪时期的灵动土家鱼（Tujiaaspis vividus）的铰接遗体表明，盔甲鱼类（骨龙类和有颌脊椎动物的姊妹类）拥有三个不配对的背鳍，一个近乎对称的脊柱下尾巴和一对连续的、从支部到尾部的副鳍。腹外侧鳍类似于其他有颌类的成对鳍瓣，特别是类似于同样拥有分化胸鳍的骨甲鱼类的腹外侧隆起。外侧鳍与脊椎动物成对附属物起源的鳍褶假说的某些方面相一致。盔甲鱼类具有甲胄鱼类和有颌类脊椎动物的先兆条件，其中成对的鳍最初是作为连续的胸骨-骨盆侧鳍出现的，计算流体动力学实验表明，这些侧鳍是被动产生的升力。只有在后来的核心谱系中，甲胄鱼类和有颌类脊椎动物的胸鳍才会向前方分化。这种后期分化之后，剩余鳍的能力领域被限制在骨盆位置，有利于主动推进和转向。
据了解，成对的鳍是一项重要的创新，它是在与活着的无颌脊椎动物分化后在有颌脊椎动物系中演化出来的。已灭绝的无颌甲胄鱼类显示了成对的体壁延伸的多样性，从骨架过程到简单的鳍瓣。相比之下，无颌动物（有颌脊椎动物的姐妹群）被解释为在胸腔位置有第一个真正的成对附属物，而骨盆附属物是后来与颌骨一起演化的。
附：英文原文
Title: Galeaspid anatomy and the origin of vertebrate paired appendages
Author: Gai, Zhikun, Li, Qiang, Ferrn, Humberto G., Keating, Joseph N., Wang, Junqing, Donoghue, Philip C. J., Zhu, Min
Issue&Volume: 2022-09-28
Abstract: Paired fins are a major innovation1,2 that evolved in the jawed vertebrate lineage after divergence from living jawless vertebrates3. Extinct jawless armoured stem gnathostomes show a diversity of paired body-wall extensions, ranging from skeletal processes to simple flaps4. By contrast, osteostracans (a sister group to jawed vertebrates) are interpreted to have the first true paired appendages in a pectoral position, with pelvic appendages evolving later in association with jaws5. Here we show, on the basis of articulated remains of Tujiaaspis vividus from the Silurian period of China, that galeaspids (a sister group to both osteostracans and jawed vertebrates) possessed three unpaired dorsal fins, an approximately symmetrical hypochordal tail and a pair of continuous, branchial-to-caudal ventrolateral fins. The ventrolateral fins are similar to paired fin flaps in other stem gnathostomes, and specifically to the ventrolateral ridges of cephalaspid osteostracans that also possess differentiated pectoral fins. The ventrolateral fins are compatible with aspects of the fin-fold hypothesis for the origin of vertebrate paired appendages6,7,8,9,10. Galeaspids have a precursor condition to osteostracans and jawed vertebrates in which paired fins arose initially as continuous pectoral–pelvic lateral fins that our computed fluid-dynamics experiments show passively generated lift. Only later in the stem lineage to osteostracans and jawed vertebrates did pectoral fins differentiate anteriorly. This later differentiation was followed by restriction of the remaining field of fin competence to a pelvic position, facilitating active propulsion and steering.
DOI: 10.1038/s41586-022-04897-6
Source: https://www.nature.com/articles/s41586-022-04897-6
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html
本期文章：《自然》：Online/在线发表
