Origin of birds
At least this clade of theropods had well-developed genuine feathers before the first known bird. Feathering in other groups of theropods is still uncertain. One compsognathid, Sinosauropteryx, has plumaceous feathers, as does Shuvuuia, another small theropod. Apparently, many small theropods carried feathers, whose function was thermoregulation (to keep warm).