We apply the Micro-XRF,which can be used to in situ non-destructively study the element distribution of the skeleton and surrounding matrix in vertebrate fossils to scan the holotype and paratype of the Middle Triassicmarine reptile Mixosauruspanxianensis (~244 Ma),visualizing the overall element distribution of the specimens. Additionally,the paratypes regions of interest are tested using a handheld X-ray fluorescence spectrometer as an adjunct. The research results show that the bone and matrix elements present a different distribution pattern. The skeleton clearly controls Ca,P,Sr and Y. The matrix where the fossil is preserved is rich in Ca,K,Fe,and Mn. In addition,Zn is variouslydistributed in different fossil bone parts of the paratype specimen,where the Zn content is higher in the trunk region than in the skull. In terms of fossil morphology,the maps clearly resolve the fossil morphology. The right forelimb and gastralium of the paratype specimen,which are invisible in regular light,are particularly well-resolved by the elemental maps. At the same time,the calcareous matrix and bone can be distinguished better. In taphonomy,comparing the elemental features of fossilized marine and terrestrial fossils demonstrates how the burial environment affects the distribution characteristics of certain elements. Th,Ce,Cu and Sr responded to the burial environment,while some elements related to bone,such as Ca,P,and Y,were less affected by the burial environment. The distribution of Zn in different bone regions was altered by bone development,and the paratype specimens centrums and ribs,where Zn is elevated,are likely to be in the stage of rapid ossification,indicating that the paratype specimen was subadult.