Why is Archaeopteryx in the theory of evolution?

Well, if you look at the skeleton of a modern bird, you will see that it has many similarities with small bipedal theropods such as Coelurus and Compsognathus. For examle, many theropods have hollow bones and even wishbones, a unique feature to birds. Also many species are covered head to toe in feathers! The unique fossilization process that allows such detail to be preserved is found the most in Liaoning, China, where most of the known feathered dinosaurs have been found. My theory is that a small, possibly tree living Coelurosaurid theropod branched out into the group Paraves (Eumaniraptora), the family that includes birds and Deinonychosaurs such as Velociraptor. All this group are very similar anatomically. The first certain bird, Archaeopteryx, shared many features with both birds and dinosaurs. It is used for the basis for bird evolution, and although another, Protoavis, evolved earlier, it is not yet agreed to be a true bird and is thought to be a chimera (Mix of two or more animals fossilized together and viewed as the same creature)