Psittacosaurus is a genus of extinct herbivorous dinosaurs that lived during the early Cretaceous period. There are several synonyms for this genus, including Hongshanosaurus, Hsiangchengosaurus, and Yunnanolepis. These synonyms were assigned to psittacosaurus specimens based on different characteristics, such as variation in skull shape or tooth morphology. Additionally, some scientists believe that certain species of psittacosaurus should be reclassified as their own genera, including Chaoyangsaurus and Diabloceratops. While the exact taxonomy of psittacosaurus and its relatives is still under debate, these synonyms highlight the complexity of classifying extinct organisms and uncovering their evolutionary relationships.