阿根廷迈蒙尼德大学Mariana Chuliver等研究人员发现，最古老的蝌蚪揭示无尾类生物生活史的演化稳定性。2024年10月30日，《自然》杂志在线发表了这项成果。

研究人员报告了来自巴塔哥尼亚中侏罗世（约1.68亿至1.61亿年前）的原始无尾类Notobatrachus degiustoi的晚期蝌蚪。这一发现具有双重重要性，因为它代表了已知的最古老蝌蚪，并且在研究人员看来是第一个原始无尾类幼虫。其精美的保存，包括软组织，展示了与现存蝌蚪特征相关的滤食机制。

值得注意的是，N. degiustoi的蝌蚪和成体均达到较大尺寸，表明原始无尾类中也发生了蝌蚪巨型化。这一新发现揭示了双相生活史，带有滤食蝌蚪栖息在水生短暂环境中，早在原始无尾类的早期演化历史中就已存在，并在至少1.61亿年内保持稳定。

据了解，无尾类生物具有双相生活史，经历水生幼体（蝌蚪）阶段，随后进入成体（青蛙）阶段，两者通过变形期连接，在此期间发生剧烈的形态和生理变化。现存的蝌蚪展现出极大的形态多样性和生态相关性，但在白垩纪前的化石记录中缺乏（超过1.45亿年前），使它们的起源和早期演化变得扑朔迷离。这与可追溯至早侏罗世的后变形无尾类化石记录形成对比，后者与晚三叠世（约2.17亿至2.13亿年前）的近亲物种相关联。

附：英文原文

Title: The oldest tadpole reveals evolutionary stability of the anuran life cycle

Author: Chuliver, Mariana, Agnoln, Federico L., Scanferla, Agustn, Aranciaga Rolando, Mauro, Ezcurra, Martn D., Novas, Fernando E., Xu, Xing

Issue&Volume: 2024-10-30

Abstract: Anurans are characterized by a biphasic life cycle, with an aquatic larval (tadpole) stage followed by an adult (frog) stage, both connected through the metamorphic period in which drastic morphological and physiological changes occur1. Extant tadpoles exhibit great morphological diversity and ecological relevance2, but their absence in the pre-Cretaceous fossil record (older than 145million years) makes their origins and early evolution enigmatic. This contrasts with the postmetamorphic anuran fossil record that dates back to the Early Jurassic and with closely related species in the Late Triassic (around 217–213million years ago (Ma))3. Here we report a late-stage tadpole of the stem-anuran Notobatrachus degiustoi from the Middle Jurassic of Patagonia (around 168–161Ma). This finding has dual importance because it represents the oldest-known tadpole and, to our knowledge, the first stem-anuran larva. Its exquisite preservation, including soft tissues, shows features associated with the filter-feeding mechanism characteristic of extant tadpoles4,5. Notably, both N. degiustoi tadpole and adult reached a large size, demonstrating that tadpole gigantism occurred among stem-anurans. This new discovery reveals that a biphasic life cycle, with filter-feeding tadpoles inhabiting aquatic ephemeral environments, was already present in the early evolutionary history of stem-anurans and has remained stable for at least 161million years.

DOI: 10.1038/s41586-024-08055-y

Source: https://www.nature.com/articles/s41586-024-08055-y