During the Great Ordovician Biodiversification Event, clarifying the biogeographic affinities , potential faunal exchanges between North China and its neighbouring blocks is pivotal to understanding trilobite diversification patterns. This study documents a Middle Ordovician trilobite fauna from the Zhongpu Formation in Yongdeng, Gansu, North China, comprising well-preserved cranidia and pygidia of 11 species belonging to 11 genera and 7 families, including one potentially new species of Pliomeridae. Trilobite biofacies anal- ysis indicates an environment of deeper shelf slope. The geometric morphometric analysis of Middle Ordovician trilobites is presented herein. Outlier analysis shows that the pliomerid species deviates significantly from 15 selected taxa of the family, expanding the known morphological variation range of Pliomeridae during the Ordovician. Comparative morphological disparity analysis with the coeval trilobite fauna from Tarim reveals substantial similarity in outline configuration and traditional metrics, indicating potential faunal exchange or ecological connectivity during the late Darriwilian. This finding provides new quantitative evidence supporting the close palaeogeographic relationship between the North China and Tarim blocks during the Middle Ordovician. The quantitative methods employed in this study can also be applied to other investigations in the fields of systematic palaeontology and morphology to provide new suggestions for palaeobiogeography from a quantitative perspective. (c) 2025 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights are reserved, including those for text and data mining, AI training , similar technologies.