Another odd and surprising thing is that the dromaeosaurs seem to be more advanced and birdlike than Archaeopteryx. (walking dinosaur costume)This is because they have a number of basic avian adaptations that earlier Archoeopteryx does not, including a more birdlike quadratojugal bone in the cheek, more hip vertebrae, very short nonoverlapping neck ribs, shorter trunks, auxiliary hooked processes on the side of the rib cage, and even more birdlike femoral heads and hip sockets. Archoeopteryx is closer to flying birds in its big forelimbs, with more backwardly angled coracoids and a big wishbone furcula. But this does not mean dromaeosaurs are less birdlike in these characters; instead, they are similar toflrghtless birds, especially the archaic ratites (ostriches and the like). Dromaeosaurs just may be secondarily flightless Cretaceous descendants of the earlier, flying archaeopterygians. This would explain why dromaeosaurs had big breastplates, a classic and advanced flight adaptation (Animatronic dinosaur).
A wide variety of bird groups of all degrees of advancement have seen members lose flight in favor of an earth-bound existence.(realistic dinosaur costume) Following the loonlike, toothy hesperornithiforme divers of the Cretaceous, there have been ostriches and their relatives, penguins, auks, the great predatory phorusrhacids of South America, flightless rails, ibises, parrots, even flightless geese, ducks, and so on. This seems to have happened with protobirds too. So, as a mainstream of flying protobirds evolved in the Late Jurassic and early Cretaceous, they may have spawned a series of ever more advanced protobird theropods that separately lost the abiliry to fly. The first full birds appear very early in the Cretaceous, and the split of the flightless protobirds from flying protobird stock should have happened before that time-perhaps in a rapid burst at the Jurassic-Cretaceous boundary.