• Archaeopteryx - The oldest known bird (150 mya) had asymmetrical feathers - it could probably fly short distances (from Germany).
• Sinosauropteryx - covered with proto-feathers and with short arms (121-135 million years ago).
• Protarchaeopteryx - Long, symmetrical feathers on arms and tail, but it probably could not fly (from China, 121-135 mya).
• Caudipteryx - a small, very fast runner covered with primitive (symmetrical and therefore flightless) feathers. (from China, 121-135 mya)
• Unenlagia - a much larger ground-dwelling theropod (from Argentina). It had flexible arm movement (up and down, like that of a bird) (90 mya).
• Velociraptor - a larger, ground-dwelling carnivore from Mongolia) with a swiveling wrist bone (this type of joint is also found in birds and is necessary for flight) (85 - 80 mya).
• Eoalulavis (from Spain) - the earliest bird that had good maneuverability while flying, even at low speeds (this extra flight control is obtained from a tuft of feathers on the thumb called the alula - it also helps in takeoffs and landings).

The longest feather-filaments were 1.5 inches long (3.8 cm). These filaments were probably used for heat insulation and were not used for flying.

It had two short fore-limbs (arms), and many sharp teeth. It ate meat like other theropods, and probably preyed upon small animals and insects. It also had a very long tail, the longest (relative to its size) of any theropod - the tail had 64 vertebrae. This tail was probably used for balance and for making quick turns.

DIET
Sinosauropteryx was a meat-eater and is the only dinosaur that has been found with a mammal in its stomach. Only the jawbone of this unidentified mammal was found in the Sinosauropteryx gut.

FOSSILS
Sinosauropteryx was found by Chinese farmers, including Li Yin Fang, in 1996 in the dry countryside near Liaoning Province, China. This area would later yield other important bird-like dinosaur finds, including Caudipteryx, Protarchaeopteryx, and also many specimens of Confuciusornis sanctus, an early bird about 120 million years old.

Three complete skeletons of Sinosauropteryx have been found, including trace fossils of small fibers (protofeathers), stomach contents, unlaid eggs, and some internal organs.

BIRDS AND DINOSAURS
The existence of Sinosauropteryx lends credence to the theory that the birds are descended from theropod dinosaurs and not from four-legged arboreal (tree living) reptiles.

OTHER FEATHERED DINOSAURS
Two new Chinese feathered dinosaurs dating from between 145 and 125 million years ago (during the late Jurassic and early Cretaceous periods) have been found in the same area of China. These fossils, Caudipteryx zoui and the more primitive Protarchaeopteryx robusta have features which are more dinosaur-like than bird-like and are considered to be theropod dinosaurs. Their feathers were symmetrical, which indicate that they could not fly (flightless birds have symmetrical feathers while those that fly have asymmetrical ones). These finds reinforce the theory that birds are descended from dinosaurs.

CLASSIFICATION
Sinosauropteryx belonged to the:

• Kingdom Animalia (animals)
• Phylum Chordata (having a hollow nerve chord ending in a brain)
• Class Archosauria (diapsids with socket-set teeth, etc.)
• Order Saurischia - lizard-hipped dinosaurs
• Suborder Theropoda - bipedal carnivores
• Infraorder Coelurosauria - lightly-built fast-running predators with hollow bones and large brains
• Superfamily Maniraptoriformes - advanced coelurosaurs with a fused wrist bone
• Family Compsognathidae
• Genus Sinosauropteryx
• Species prima (the type species).