Abstract: Theropod footprint assemblages from the Sanjianfang Formation (Middle Jurassic) at the Shanshan tracksite, Turpan City, Xinjiang, northwest China are documented and re-described in detail. Together with new discoveries from this locality, they shed light on the different preservation and extramorphological variation of a total of 143 footprints. Ichnotaxonomically, they are assigned to the ichnospecies Changpeipus carbonicus, well known from other Jurassic tracksites of China. The presence of two distinct morphotypes, as has been proclaimed in earlier studies, is related to extramorphological variation on surfaces that indicate a soft, wet and slippery substrate. Anatomically based features supporting different ichnospecies are not present. Furthermore, the comparison with similar footprints from other localities suggests a monotypic ichnogenus Changpeipus with the type speciesC. carbonicus. Footprint lengths of 12.2 cm (a few isolated examples) to 47 cm at the Shanshan tracksites reflect small to medium-sized trackmakers that can be interpreted either as different age classes or different biological species. Peculiar preservational features include a footprint that documents slipping movement of the pes by three parallel bands obviously reflecting digits II, III and IV. An associated “normally” impressed tridactyl footprint suggests that both constitute a single step. The depositional environment was a gradually expanding and deepening lacustrine setting. This is also supported by the co-occurrence of abundant invertebrate trace fossils. Contrary to earlier interpretations resulting in an assignment to Lockeia the invertebrate traces are re-assigned here to the ichnogenus Fuersichnus that can be attributed to deposit-feeding insect larvae or other invertebrates. Fuersichnus is a characteristic dwelling and/or feeding burrow of muddy floodplains or lake margin settings.

摘要： 详细描述了中国西北部新疆吐鲁番市鄯善足迹点、中侏罗统三间房组的兽脚类足迹组合。连同新发现在内，共描述了143个足迹，并阐明其不同的保存状况与额外形态变化。在足迹分类学上，这批足迹被归入石炭张北足迹(Changpeipus carbonicus), 该足迹种常见于中国其他侏罗纪足迹点。前人的研究认为此地有两种不同的足迹形态，但研究表明这是由软且湿滑的基底造成的额外形态变化。足迹的结构特征亦不支持此地存在不同的足迹种。此外，对比了其他化石点类似的足迹，认为张北足迹为单型属，即模式种石炭张北足迹。鄯善足迹点的足迹长度从12.2 cm (几个孤立的样本)到47 cm, 足迹应由不同年龄段的、小型至中型的同类造迹者或不同类的造迹者所留。奇异的足迹状态包括了一个滑动造成的足迹，足迹由三道平行条带构成，条带应为第II, III和IV趾所留。一个与其关联的“正常”足迹可能与该滑动足迹构成一个单步。与足迹共生的、丰富的无脊椎动物遗迹化石支持该化石点的沉积环境是一个逐步扩大和深化的湖泊。前人的研究将此地的无脊椎动物遗迹化石归入洛克迹(Lockeia), 新的研究将其归入福尔斯迹(Fuersichnus), 这类遗迹被归于泥食性昆虫幼虫或其他无脊椎动物所留。福尔斯迹指示的环境特征是在泥泞的河漫滩或湖泊边缘居住与/或觅食。