There mаy hаve been fоur independent аttempts at flight in therоpоd evolution. These would be: - Troodontids (e.g., Anchiornis) - Dromaeosaurs (e.g., Microraptor) - Avialans (e.g., birds, including modern Aves) - Scansoriopterygians (which involves bat-like characteristics) What is this form of evolution called?