由衍生的茎四足动物揭示的陆生解剖学的进化，这一成果由英国牛津大学Ben Igielman课题组经过不懈努力而取得。该研究于2026年9月30日发表于国际一流学术期刊《自然》杂志上。

四足动物（有肢脊椎动物）包括滑体两栖类和羊膜动物，目前占所有脊椎动物物种的一半，在陆地上尤为重要。四肢最早出现在晚泥盆世（约3.65亿年前）的干群四足动物中。然而，许多类群要么具有鳍样功能解剖结构的四肢，要么次生失去了四肢，这引发了关于四足动物四肢的生态背景和早期演化的问题。在此，研究人员提供了关于神秘的早石炭世Westlothiana lizziae的大量新数据，该物种被广泛引用为最早适应陆地生活的干群羊膜动物。他们发现了颅顶、腭、脑颅和下颌的意外祖征，同时还有水生适应特征，包括骨化的内鳃骨骼以及腭和下颌上广泛的齿状小突起。这些特征在系统发育分析中使Westlothiana回归为干群四足动物，表明诸如羊膜动物样的趾式、鳍样前肢功能的丧失以及表面上爪样的末端指节等陆生适应是以镶嵌方式演化的，并且这些特征是在四足动物冠群起源之前的过渡性两栖环境中演化的。研究人员的发现支持了最近关于一个分类学上包容性的四足动物干群谱系的建议，但也揭示了解剖学知识中的重大空白，尤其是对于小型类群，这些空白阻碍了对早期四足动物演化的理解。

附：英文原文

Title: Evolution of terrestrial anatomy revealed by a derived stem tetrapod

Author: Igielman, Ben, Jenkins, Xavier, Head, Jason, Fernandez, Vincent, Roberts, Lucy, Smithson, Timothy, Benson, Roger

Issue&Volume: 2026-09-30

Abstract: Tetrapods (limbed vertebrates) include lissamphibians and amniotes, and now comprise half of all vertebrate species, with particular importance on land. Limbs first appeared in stem tetrapods by the Late Devonian, 365 million years ago1,2,3,4,5. However, many taxa either have limbs with fin-like functional anatomy or have secondarily lost them, raising questions about the ecological context and early evolution of the tetrapod limb6. Here we provide considerable new data on the enigmatic Early Carboniferous Westlothiana lizziae, widely cited as the earliest terrestrially adapted stem amniote7,8. We find unexpected plesiomorphies of the skull roof, palate, braincase and mandible, alongside aquatic adaptations, including an ossified internal gill skeleton and extensive denticles on the palate and mandible. These traits return Westlothiana as a stem tetrapod in our phylogenetic analyses, demonstrating that terrestrial adaptations such as an amniote-like pedal formula, loss of fin-like forelimb function and superficially claw-like terminal phalanges evolved in a mosaic fashion, and that these traits evolved in a transitional, amphibious context before the origin of the tetrapod crown group. Our findings reinforce recent suggestions of a taxonomically inclusive tetrapod-stem lineage, but also illuminate substantial gaps in anatomical knowledge, especially for small-bodied taxa, that obstruct our understanding of early tetrapod evolution.

DOI: 10.1038/s41586-026-11090-6

Source: https://www.nature.com/articles/s41586-026-11090-6