Lower Triassic bivalve assemblages are recognized in the Yinkeng Formation, South China, and the Hong Ngai Formation, North Vietnam. Basinal mudstones and deep ramp carbonates contain the monospecific Claraia wangi assemblage. The Eumorphotis teilhardi-Towapteria scythica assemblage occurs in deep ramp deposits. The Claraia stachei-“Claraia” phobangensis assemblage is found in shallow ramp deposits. These bivalve assemblages are mainly composed of epifaunal species, and are characterized by low species diversity and parautochthonous elements. Most species of Claraia probably inhabited shallow to deep marine environments. Besides, Eumorphotis and Towapteria are useful indicators of Lower Triassic shallow marine environments above storm-wave base.