Data from: Are palaeoscolecids ancestral ecdysozoans?

The reconstruction of ancestors is a central aim of comparative anatomy and evolutionary developmental biology, not least in attempts to understand the relationship between developmental and organismal evolution. Inferences based on living taxa can and should be tested against the fossil record, which provides an independent and direct view onto historical character combinations. Here, we consider the nature of the last common ancestor of living ecdysozoans through a detailed analysis of palaeoscolecids, an early and extinct group of introvert-bearing worms that have been proposed to be ancestral ecdysozoans. In a review of palaeoscolecid anatomy, including newly resolved details of the internal and external cuticle structure, we identify specific characters shared with various living nematoid and The reconstruction of ancestors is a central aim of comparative anatomy and evolutionary developmental biology, not least in attempts to understand the relationship between developmental and organismal evolution. Inferences based on living taxa can and should be tested against the fossil record, which provides an independent and direct view onto historical character combinations. Here, we consider the nature of the last common ancestor of living ecdysozoans through a detailed analysis of palaeoscolecids, an early and extinct group of introvert-bearing worms that have been proposed to be ancestral ecdysozoans. In a review of palaeoscolecid anatomy, including newly resolved details of the internal and external cuticle structure, we identify specific characters shared with various living nematoid and祖先重建是比较解剖学（comparative anatomy）与进化发育生物学（evolutionary developmental biology）的核心研究目标之一，在解析发育演化与生物个体演化的关联时尤为关键。基于现生分类群的演化推论可且应当借助化石记录进行验证，化石记录可为认识历史性状组合提供独立且直接的视角。本研究通过详细分析古钵虫类（palaeoscolecids）——一类已灭绝的早期具翻吻蠕虫，曾被提议为蜕皮动物（ecdysozoans）的祖先类群——探讨现生蜕皮动物的最近共同祖先的特征。在综述古钵虫类解剖结构（包括新解析的内外角质层细节）的基础上，我们识别出与多种现生线形动物共有的特定性状