“Pelycosaur”-grade synapsids were a successful group of terrestrial tetrapods that lived during the Carboniferous and Permian, utilising a wide diversity of ecological niches. They are considered the trackmakers of the ichnogenera Dimetropus and possibly also Dromopus and Tambachichnium, found in upper Palaeozoic deposits of North America, North Africa and Europe. Here we describe a new morphotype from the lower Permian of Mallorca (Balearic Islands, western Mediterranean), identified as cf. Dimetropus isp., which was purportedly produced by caseid synapsids. The trackmaker identity is inferred based on the digit proportions, as caseids are the only pelycosaurs with species showing mesaxonic autopodia, and a relative depth pattern (corresponding to the functional prevalence of the autopodia of the trackmaker) showing an overall similarity to that of Dimetropus osageorum, which is also attributed to caseids. A detailed study of the expulsion rims and drag traces makes it possible to infer the mode of locomotion of the trackmaker, with a gait alternating the movement of manus and pedes of the two sides of the body and lateral undulation of the spine. Our results provide new information concerning the locomotion of early synapsids, which would undergo important functional modifications later in their evolutionary history such as a shift from abducted to adducted posture and lateral to sagittal bending of the axial skeleton.

“盘龙”级联足动物是一组成功的陆生四足动物，它们生活在石炭纪和二叠纪，利用了广泛多样的生态位。它们被认为是 ichnogenera Dimetropus 的追踪者，也可能是Dromopus和Tambachichnium，它们发现于北美、北非和欧洲的上古生界沉积物中。在这里，我们描述了来自马略卡岛（巴利阿里群岛，地中海西部）下二叠纪的新形态类型，确定为 cf。异形体isp.，据称是由 caseid synapsids 产生的。追踪者的身份是根据数字比例推断出来的，因为 caseids 是唯一一种显示中轴自足的盘龙类，相对深度模式（对应于追踪者的自足的功能普遍性）显示出与Dimetropus osageorum的总体相似性，这也归因于酪蛋白。对排出边缘和拖曳痕迹的详细研究可以推断出追踪者的运动模式，其步态交替着身体两侧的手足运动以及脊柱的横向波动。我们的研究结果提供了有关早期突触类运动的新信息，这些突触类动物将在其进化历史的后期经历重要的功能修改，例如从外展姿势转变为内收姿势以及轴向骨骼的横向向矢状弯曲。