Birds are direct descendants of small theropod dinosaurs.

Fossil evidence and genetic studies confirm that birds evolved from a group of small, feathered theropod dinosaurs during the Late Jurassic and Early Cretaceous periods. Key fossils like Archaeopteryx show a mix of dinosaur and bird features, including feathers, wishbones, and three-fingered hands. Modern birds share many skeletal and molecular traits with these theropods, solidifying their place as living dinosaurs.