Oviraptorosaurs ("egg thief lizards") are a group of beaked, feathered dinosaurs from the Cretaceous Period of what are now Asia and North America. The group includes the Oviraptoridae, the Caenagnathidae and several species which do not belong to either of these families, including Avimimus, Caudipteryx, and Protarchaeopteryx. The group is close to the ancestry of birds and it has been suggested that they may in fact represent primitive flightless birds.