Paleontologists have discovered two new bird-like dinosaurs with rudimentary feathers and many other bird-like features. These finds reinforce the theory that birds evolved from dinosaurs. Although these new species had some form of primitive feather, these feathers were symmetrical in cross-section which made then useless for flight (asymmetry is neccessary to provide lift). The dinosaurs' arm-length was also insufficient for flight. The feathers were probably used as insulation, keeping in body heat.
These new dinosaurs Protarchaeopteryx robusta, and Caudipteryx zoui, together with the recently found Sinosauropteryx prima, have characteristics common to both theropod dinosaurs and to birds. All three, plus many specimen of a very primitive bird (Confuciusornis sanctus) were found in the period from 1996 to 1997 in an ancient lake bed in Liaoning Province, in northestern China.
One of the primary researchers, Philip J. Currie from the Royal Tyrrell Museum of Paleontology in Drumheller, Alberta, Canada said, "This is the most important discovery of the century. The credibility of the dinosaurs-to-birds theory has just taken a giant leap ahead with these specimens." Currie worked with an international team of scientists: Ji Qiang, director of the National Geological Museum of China; Mark Norell, chairman and associate curator, Department of Vertebrate Paleontology, American Museum of Natural History, New York; and Ji Shu-An, of the National Geological Museum of China.
In the chain of creatures leading from theropod (dromaeosaurid) dinosaurs to birds, Sinosauropteryx is the earliest bird-like dinosaur. For now, the bird-like animals include (in chronological order):
- Archaeopteryx - The oldest known bird had asymetrical feathers - it could probably fly short distances and was the size of a crow. This bird was probably an evolutionary dead-end. (from Germany, 150 mya).
- Sinosauropteryx prima - (121-135 million years ago). Sinosauropteryx had a coat of downy, feather-like fibers that are perhaps the forerunner of feathers. This ground-dwelling dinosaur had short arms, hollow bones, a three-fingered hand, and was about the size of a turkey.
- Protarchaeopteryx robusta - Long, symmetrical feathers on arms and tail, but it probably could not fly. It was the size of a turkey (from China, 121-135 mya).
- Caudipteryx zoui - a small, very fast runner covered with primitive (symmetrical and therefore flightless) feathers on the arms and tail, with especially long ones on the tail. It was about the size of a turkey. (from China, 121-135 mya)
- Unenlagia comahuensis
- a much larger ground-dwelling theropod about 4 feet (1.2 m) tall and 8 feet (2.4 m) long. It had flexible arm movement (up and down movements were possible, like that which a bird uses in flying). (from Argentina, 90 mya).
- Velociraptor - a larger, ground-dwelling carnivore with a swiveling wrist bone (this type of joint is also found in birds and is necessary for flight). About 3 feet tall (1 m). (from Mongolia, 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).
OTHER DINOSAUR-BIRD FOSSILS
Birds probably evolved from the maniraptors
, a branch of bird-like dinosaurs. The Archaeopteryx is the oldest known fossil bird, and dates from the late Jurassic period (about 150 million years ago), now extinct. Although it had feathers and could fly, it had similarities to dinosaurs, including its teeth, skull, and certain bone structures.
RELATED LINKS:
Information about Sinosauropteryx prima.
Information about Caudipteryx zoui.
A page on Protarchaeopteryx robusta.
Information on Unenlagia comahuensis.
Other fossils found in China.
A site about Birds.
A Chart of geological time.
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