How are birds and dinosaurs closely related?

Birds are direct descendants of dinosaurs and are considered by many to be dinosaurs. Birds emerged in the later Jurassic period, branching of from a group of dinosaurs called theropods, two legged animals that accounted for all carnivorous dinosaurs. Many theropod dinosaurs show birdlike traits (including feathers on many species), particularly dromaeosaurs such as velociraptor.