Scientific Name: Osteichthyes and Keichousaurus hui Geological Period: Late Triassic to Early Cretaceous A fossil of a small reptile and fish, commonly found in Guizhou, China, primarily in Late Triassic (approximately 230–200 million years ago) or Jurassic (approximately 201–145 million years ago) sedimentary layers. This fossil not only preserves the complete morphology of Osteichthyes and Keichousaurus hui, but also records a real-life scene of Mesozoic freshwater ecology, providing valuable physical evidence for the study of paleoecosystems.