Abstract: Based on an articulated skeleton, a new genus and species of cyamodontoid placodont Sinocyamodus xinpuensis is erected. As the first placodont discovered in China (Guanling, Guizhou Province), S. xinpuensis was collected from the first member of the Wayao Formation, which was considered to be the early Late Triassic. The diagnosis of the new genus and species could be generalized as following: Relatively small cyamodontoid placodont; orbital distinctly elongated (the raüo of the longitudinal diameter of the upper temporal fossa to that of the orbit is 1.23); rostrum short and rounded; premaxilla with 3 bulbous teeth; carapace does not cover pectoral and pelvic girdiles; limbs and tail covered with osteoderms; humerus with a distinct and distally notched ectepicondylar groove; entepicondylar foramen absent; phalangeal formula in manus 2—3—4—4—3(2—3—4—4—?2 in pes). For a long time the distribution of placodonts has been restricted to coastal stretches of westem periphery of the Triassic Tethys and epicontinental seas of central Europe. Traditionally this group was considered to have originated from the Germanic Basin at the end of the Early Triassic, and then spread to western periphery of the Triassic Tethys. The early existence of cyamodontoid in the lower Anisian of Israel raises the question of whether placodonts reached Europe from the east or outspread from Europe toward the east. Rieppel (1995) proposed an eastern rather than a western Tethyan center of the origin of the Sauropterygia, including the placodonts and the eosauropterygia and further explained their fossil distribution by an eastward expansion into the eastern Pacific Province and a westward expansion into the western Tethyan Province, The discovery of S xinpuensis in southwestern China represents the first occurrence of placodonts in eastern Tethyan Province, where more forms are expected to be discovered from older deposits. Until now, all major groups of Triassic marine reptiles including nothosaurs, ichthyosaurs (Li, 1999) and thalattosaurs (Rieppel et al., 2000) in western Tethys are mirror-imaged in southwestern China. The South China block, which is geographically situated between the western Tethyan and the eastern Pacific domains may put up mixed faunal affinities of both trans-Pacific and western-Tethyan. Based on vertebrate fossils the relationship to trans-Pacific fauna was weakly supported by some fragmentary materials from southem China and Wyoming (Rieppel, 1999), and the western-Tethyan relationship appeared to be much better supported by this new fauna, especially the cyamodontoid placodont described above, which has not been found in northern America by far. This comparability indicates that there was a lot faunal interchange between the west Tethy and southwest China in the early Late Triassic.