Pair Matrix – One Large and One Small Large Guizhouosaurus huiziensis: 25 cm Small Guizhouosaurus huiziensis: 8 cm This is an exceptionally well-preserved fossil of *Guizhouosaurus huiziensis*, discovered in Late Middle Triassic marine strata in Guizhou, China (approximately 240 million years ago). This pair of shale fossils contains three individuals, which is extremely rare: A larger individual is located in the middle, gracefully posed, with a complete skeleton including ribs, a slender neck, limbs, and a tail. The other is likely a juvenile individual or a smaller individual belonging to the same group. Guizhouosaurus huiziensis is one of the most representative marine reptiles of the Triassic period in China, known for its slender body, long neck, and adaptations to aquatic life. This specimen not only has well-preserved skeletons but also provides potential clues to understand the social behavior and reproductive ecology of early marine reptiles.