The Cretaceous strata of Zhejiang Province yielded abundant dinosaur bone, egg, and track fossils, documenting diverse terrestrial dinosaur assemblages in southeastern China. Herein we report new tridactyl theropod tracks from the mid-Cretaceous Chaochuan Formation at Shang’antian Village, Dongyang City, Zhejiang Province. Two distinct morphotypes of theropod tracks are identified, representing the first record of these ichnotypes in Zhejiang Province. Morphotype 1 is referred to Grallator isp., characterized by small, slender mesaxonic tracks with a high length/width ratio and narrow interdigital divarication. Morphotype 2 is referred to cf. Asianopodus isp., characterized by a prominent metatarsophalangeal pad aligned along the axis of digit III, a lower length/width proportion, and much wider interdigital angles compared with Grallator. Multiple parallel trackways of cf. Asianopodus isp. with consistent orientation and uniform spacing demonstrate gregarious behavior of small-sized arctometatarsalian theropods, likely ornithomimosaurs, during the mid-Cretaceous in southeastern China, representing only the second global record of group behavior in Asianopodus-type theropods. This new track assemblage enriches the Cretaceous dinosaur ichnofossil record of Zhejiang, provides new evidence for regional stratigraphic correlation, and offers new insights into the paleobiology, taxonomic composition, and behavioral ecology of southeastern Chinese mid-Cretaceous theropod communities.

Dongyang City, Zhejiang Province, Chaochuan Formation, Cretaceous, theropod tracks, gregarious behavior, vertebrate ichnology

浙江省白垩纪地层产出大量恐龙骨骼、蛋化石与足迹化石，记录了我国东南部多样的恐龙动物群。报道发现于浙江省东阳市上安恬村，白垩纪中期朝川组新的三趾兽脚类恐龙足迹。研究识别出的两类兽脚类足迹，均为浙江省内首次发现的足迹类型。第一类足迹归为未定种跷脚类足迹（Grallator isp.），特征为整体小巧纤细、中轴突出，长宽比值高；趾间张开角度较窄，但相较于典型跷足迹略宽。第二类足迹为近似亚洲足迹未定种（cf. Asianopodus isp.），特征为沿第三趾中轴线发育一块膨大的跖趾垫，足迹长宽比例更低，趾间分叉角度远大于跷脚类足迹。近似亚洲足迹保存多条走向一致、间距均匀的平行行迹，表明该类小型夹跖型兽脚类(大概率为似鸟龙类)在白垩纪中期的中国东南部具有集群活动习性，这也是全球范围内亚洲足迹型恐龙存在集群行为的第二例化石证据。本次发现的足迹组合丰富了浙江白垩纪恐龙足迹化石材料，为区域地层对比提供了新依据，同时对我国东南地区白垩纪中期兽脚类恐龙类组成、古生物特征与行为生态的认识提供了新材料。