The dino-bird link
Discussions by Yann Oliver
The hypothesis that birds are derived from dinosaurs is now clearly established. It had been considered as impossible from roughly the twenties to the seventies, mainly because of a lack of clavicles in dinosaurs, while a strong furcula (fusion of the clavicles) is essential in flight. Some dinosaurs are now known to have had such a furcula. Archaeopteryx is actually very close to some dinosaurs such as deinonychosaurs.
But a nearly definite proof in favour of a dinosaur-bird link is the recent discovery of animals which are clearly dinosaurs, but covered with feathers. There are five of them known today (from the same region of China), but it is rumoured there could be more.
Incidentally, these dinosaurs seem to hint for a terrestrial (through fast running) rather than tree-dwelling origin of flight.
In fact, some paleontologists think that some dinosaurs might even be descended from primitive birds and come back to a terrestrial life.
Archaeopteryx and its links to both birds and dinosaurs, and the wishbone debate.
The feathered dinosaurs. A description of the feathered theropods, and a discussion about the skin of dinosaurs.
The origin of flight. The cursorial versus arboreal debate, and relationships among early birds and bird-like theropods.
Archaeopteryx and its links to both birds and dinosaurs,
Dinosaurian features of Archaeopteryx
The wishbone debate
Three problems, and answers
The feathered dinosaurs
Feathers versus scales
Description of the feathered theropods
The origin of flight
Cursorial or arboreal
Relationships among early birds and bird-like dinosaurs