Evolution of Birds
The Theropods originally had four digits which was reduced to three. They then developed hollow cylindrical feathers which changed to tufted feathers, and finally feathers closed with barbule and hooks. Feathers eventually closed and became asymmetrical and the ulna in the wings were longer than the femur. In the modern bird, a toothless beak, fused digits and a short feathered tail is present. In the process, many bones were fused which helped the efficiency of flight.
Crocodiles are the closest living relatives to birds. They are however said to be stuck in the past as they have a slow rate of genetic evolution. The body structure of the crocodiles