Based on fossil and biological evidence, most scientists accept that birds are a specialized sub-group of theropod dinosaurs.More specifically, they are members of Maniraptora, a group of theropods which includes dromaeosaurs and oviraptorids, among others.[11] As scientists discover more non-avian theropods that are closely related to birds, the previously clear distinction between non-birds and birds has become blurred. Recent discoveries in the Liaoning Province of northeast China, which demonstrate that many small theropod dinosaurs had feathers, contribute to this ambiguity