Feathered dinosaur

A feathered dinosaur is any species of dinosaur possessing feathers. That includes all species of birds, but there is a hypothesis that many, if not all, non-avian dinosaur species also possessed feathers in some shape or form. That theory has been challenged by some research.

It has been suggested that feathers had originally functioned as thermal insulation, as it remains their function in the down feathers of infant birds today prior to their eventual modification in birds into structures that support flight.

Since scientific research began on dinosaurs in the early 1800s, they were generally believed to be closely related to modern reptiles such as lizards. The word dinosaur itself, coined in 1842 by paleontologist Richard Owen, comes from the Greek for 'terrible lizard'. That view began to shift during the so-called dinosaur renaissance in scientific research in the late 1960s, and by the mid-1990s, significant evidence had emerged that dinosaurs were much more closely related to birds, which descended directly from the theropod group of dinosaurs.

Knowledge of the origin of feathers developed as new fossils were discovered throughout the 2000s and the 2010s, and technology enabled scientists to study fossils more closely. Among non-avian dinosaurs, feathers or feather-like integument have been discovered in dozens of genera via direct and indirect fossil evidence. Although the vast majority of feather discoveries have been in coelurosaurian theropods, feather-like integument has also been discovered in at least three ornithischians, suggesting that feathers may have been present on the last common ancestor of the Ornithoscelida, a dinosaur group including both theropods and ornithischians. It is possible that feathers first developed in even earlier archosaurs, in light of the discovery of vaned feathers in pterosaurs. Fossil feathers from the dinosaur Sinosauropteryx contain traces of beta-proteins (formerly called beta-keratins), confirming that early feathers had a composition similar to that of feathers in modern birds. Crocodilians also possess beta keratin similar to those of birds, which suggests that they evolved from common ancestral genes.