Therapod

Are there any studies on this subject and if so, please post findings.

Lots. Recently, there are many fossils of feathered theropods discovered in a deposit of fine Chinese, things like Sinosauropteryx, Caudipteryx and Beipiaosaurus (look on wikipedia). They are younger than the famous Archaeopteryx, which has a reptile skull, teeth, digits, claws, vertebrae, sternum, ribs, pelvis and tail, a bird and a few features, like a triangle, the wings and feathers. However, the elderly and theropods have many characteristics Archeopteryx skeletal and feathers therapods add further support to the relationship. In young sediments than Archaeopteryx, there are several fossil species with more features like birds, such as Sinornis and Shenzhouraptor and dozens of others (wikipedia "fossil birds).