Isolated theropod teeth are frequently found in geological formations and can provide valuable information for paleoecology. Here we describe an isolated theropod tooth from the Lower Cretaceous Lianmuqin Formation in Wuerho (Urho), Xinjiang, Northwestern China. The tooth has a crown height of 30.36 mm, indicating a medium-sized species. The tooth exhibits ziphodont morphology, with smooth enamel, sub-rectangular distal denticles, and a mesial carina restricted to only the apical third with dot-like denticle remnants. The combined evidence from our cladistic and discriminant analyses supports its referral to the clade Tetanurae, although a more specific classification remains elusive. However, morphological comparisons suggest it does not belong to any known theropod from the Wuerho Pterosaurian Fauna. The medium-sized theropod represented by this tooth fills a previously unrecognized ecological niche as a secondary predator in the region’s Early Cretaceous ecosystem.

孤立的兽脚类牙齿在地层中较为常见，可以为古生态研究提供重要信息。中国西北新疆乌尔禾区下白垩统连木沁组发现的一枚孤立兽脚类牙齿。该牙齿齿冠高为30.36 mm, 代表一中体型兽脚类。此牙齿为扁锯齿型，牙釉质表面光滑，远端锯齿近矩形，近端齿嵴仅限于齿冠顶部约1/3处，无锯齿，但有点状锯齿残留。结合本次研究的系统发育分析与判别分析，该牙齿被归入坚尾龙类，但并未确定更细致的分类。形态对比显示，此坚尾龙类牙齿不属于以往在该动物群内已发表的兽脚类恐龙。这枚牙齿所代表的中型兽脚类恐龙可能占据了以前未被识别出的生态位，即作为这一区域的次级捕食者存在。