During the 19th century, birds were found to share some similar characteristics with birds. This was after the discovery of a primitive bird known as Archaeopteryx. It was not until the late 90s when the fossils of non avian dinosaur were discovered with an interesting characteristic of well preserved feathers. Since then, most dinosaurs mostly in the class of theoropods have been discovered with the characteristic of having been feathered. Early feathers by animals were used for hunting rather than flight. This is because of the slow development of the consumption chain.
As a result of Charles Darwin's theory of evolution, other biologists and evolution defenders came up with different theories concerning feathered disciples. One such biologist was Thomas Henry made a research proposal suggesting that birds were descendants of dinosaurs. Thomas suggested that the skeletal structure of Compsognathus which is a type of a dinosaur shared similar characteristics with the skeletal characteristics of the first bird Archaeopteryx lithographica.
So many theories have been developed directly linking birds to dinosaurs. According to Long, other skeletal similarities between the birds and the dinosaurs include the arms, pectoral girdle and the clavicle (Long & Schouten, pg.16). This results to the conclusion that some of the theoropod dinosaurs might have been feathered. Modern paleontologists today suggest that birds are the surviving dinosaurs of current time from the evolution lineage of non-avian dinosaurs.
During the 90s, there has been continuous discovery of fossil evidence of feathered dinosaurs. Most of these fossils were preserved in lagerstatte which is a sedimentary rock. Most of these discoveries were made in Liaoning in China and have showed close relationship between birds and dinosaurs. Another early type of dinosaur known as oviraptorosaur indicated birdlike characteristics such as folded forearms similar to birds.
Critics argue that the fossils discovered in China may not have been genuine fossils but preserved artifacts. A fossil of Archeoraptor liaoningensis which turned out to be a forgery have questioned the authenticity of these fossils. However, most fossil feather specimens have been found to share similar characteristics suggesting the existence of feathered dinosaurs as well as birds and dinosaur sharing a common ancestry. This shows that the development of feathers was for flight purposes rather than as a result of environmental selection.