Eurypterids (sea scorpions) are a group of extinct, marine euchelicerates that have an extensive Palaeozoic record. Despite lacking a biomineralised exoskeleton, eurypterids are abundantly preserved within select deposits. These collections make statistical analyses comparing the morphology of different genera possible. However, eurypterid shape has not yet been documented with modern geometric morphometric tools. Here, we summarise the previous statistical assessments of eurypterid morphology and expand this research by presenting landmark and semi-landmark analyses of 115 eurypterid specimens within the suborder Eurypterina. We illustrate that lateral compound eye morphology and position drives specimen placement in morphospace and separates proposed apex predators from more generalist forms. Additionally, evidence for size clusters in Eurypterus that may reflect ontogeny is uncovered. We highlight the use of geometric morphometric analyses in supporting the naming of new taxa and demonstrate that these shape data represent a novel means of understanding inter-generic ontogenetic trajectories and uncovering developmental changes within the diverse euarthropod group.

Eurypterids（海蝎子）是一组已灭绝的海洋euchelicerates，具有广泛的古生代记录。尽管缺乏生物矿化的外骨骼，但广翅目大量保存在选定的矿床中。这些集合使统计分析比较不同属的形态成为可能。然而，现代几何形态测量工具尚未记录 eurypterid 的形状。在这里，我们总结了以前对大翅目形态的统计评估，并通过对大翅目亚目内的 115 个大翅目标本进行标志性和半标志性分析来扩展这项研究。我们说明横向复眼形态和位置驱动标本在形态空间中的放置，并将提议的顶端捕食者与更通才的形式分开。此外，关于规模集群的证据发现了可能反映个体发育的Eurypterus 。我们强调使用几何形态学分析来支持新分类群的命名，并证明这些形状数据代表了一种理解跨属个体发育轨迹和揭示不同真节肢动物群内发育变化的新方法。