Abstract: Tubiphytes bonded reef developed on the edge of the Anisian Stage( Middle Triassic) isolated platform in Luodian area, southwestern Guizhou, among which Tubiphytes, as a tubular fossil with controversial affinity, appeared since Paleozoic, and a new genus and species appeared after crossing the P/T extinction line. Outdoor field measurements were conducted on Mingtang section in the study area, samples were collected, thin sections were identified indoors, and sedimentary records were analyzed from macro to micro perspectives to characterize fossil characteristics. Five genera and Seven species of Tubiphytes were identified, and the main reef-building organisms were Tubiphytes obscurus, Tubiphytes ramosus sp. , Plexoramea gracilis and Plexoramea cerebriformis
, accounting for more than 90% of the total reef-building organisms. This kind of tubular fossils can't be classified as a single organism, and their existence and genesis represent extremely complex composition and morphological function. Their reef-building may involve the adhesion and calcification of algae bridges led by cyanobacteria. This study provides new materials for the restoration of reef-building organisms in the Middle Triassic, and also fills the gap in the study of Anian reefs on the edge of isolated platforms.

reef-build organisms, Tubiphytes reef, Middle Triassic, Mingtang section, Guizhou province