It has long been thought that birds are descended from theropod dinosaurs with Archaeopteryx considered to be a classic intermediate between the two groups. The discovery of small theropod dinosaurs with "protofeathers" in the 1990s was seen as confirmation that birds are descended from dinosaurs. More recently, many feathered theropods have been discovered in China and have been interpreted as showing how birds evolved from theropod dinosaurs. Some scientists have questioned the existence of "protofeathers" and feathers on some of these creatures, and others have suggested that feathered theropods are birds. This critical analysis of the fossils reviews the evidence for feathered theropods and compares them to living and extinct birds. An informal classification of the feathered fossils is suggested.