WASHINGTON—Two fossil animals with distinct feathers found in northeastern China help substantiate the theory that birds evolved directly from small, carnivorous, ground-dwelling dinosaurs.

The animals, whose feathers spring from bodies that have many dinosaur features, were discovered in the rich fossil beds of China’s Liaoning Province, the source of two other major discoveries in recent years. More than 120 million years old, they support the thinking of most paleontologists: Birds are dinosaurs.

The discoveries are reported in the July NATIONAL GEOGRAPHIC magazine, and the animals are described in the June 25 issue of Nature magazine in an article by Ji Qiang and Ji Shuan of China, Philip Currie of Canada and Mark Norell of the United States.

The two fossil species are to be unveiled at a news briefing Tuesday at the National Geographic Society. They and fossils of two other species from Liaoning will be on display for the first time outside China in the Society’s Explorers Hall museum June 24 through July 26.

One of the new animals has been named Protarchaeopteryx robusta and is more primitive than Archaeopteryx, the earliest known bird. Its feathers are symmetrical, suggesting it could not fly, the scientists say. It may be how the ancestors of Archaeopteryx looked. The other new animal is called Caudipteryx zoui. Its feathers show up distinctly in the fossil, especially on the arms and tail. A speedy runner, Caudipteryx was covered with primitive feathers that lacked the aerodynamic quality necessary for flight.

“The feathers of Protarchaeopteryx and Caudipteryx seal their relationship to the earliest known birds,” Currie writes in NATIONAL GEOGRAPHIC. But “in their body form they look...more like those slender, meat-eating dinosaurs called theropods.”

Identification of Caudipteryx was made by Currie, curator of dinosaurs at the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta. It occurred when he and assistant Kevin Aulenback were in Beijing examining three specimens identified as Protarchaeopteryx with Ji Qiang, director of China’s National Geological Museum.

They noticed inconsistencies among the fossils. For instance, the animals were the same size and all had body feathers, but two of them had much shorter arms than the third. The two short-armed specimens had teeth that were long and sharp, with deep, bulbous roots, unlike the other’s conical shape. In another inconsistency, the teeth of the short-armed form were confined to the front of the upper jaw, pointing more forward than down.

Convinced they had a new species, the scientists named it Caudipteryx— “tail feather”—for the tall plumes that the creature likely fanned for display. Caudipteryx becomes the fourth “feathered” animal to be found near the tiny village of Sihetun in Liaoning Province. It joins Protarchaeopteryx and Confuciusornis—a creature with relatively short, clawed wings that was probably one of the first birds to fly well—and Sinosauropteryx, one of the most important dinosaur finds of the 20th century.

“The discoveries of those feathered creatures from the western part of Liaoning Province, northeast China, certainly support the hypothesis that birds were derived directly from small theropod dinosaurs,” Ji said. “They make the relationship between dinosaurs and birds closer and closer, but they also make the definition and concept of birds more and more indistinct.”

The link between dinosaurs and birds was first noted by naturalist Thomas Henry Huxley in the mid-1800s. In the 1970s John Ostrom of Yale University launched a meticulous comparison of the anatomical details of Archaeopteryx with those of dinosaurs. He concluded that Archaeopteryx resembled a scaled-down version of the theropod dinosaur known as Deinonychus.

Ostrom pointed in particular to a small, distinctive half-moon-shaped wrist bone shared by the two creatures, which allowed them both to pivot their hands in similar fashion—critical for flapping flight. “Dinosaurs did not become extinct,” Ostrom proclaimed. They live today in feathered form, as swallow, hawk, hummingbird, magpie.

In recent decades several birdish dinosaurs and dinosaur-like birds have turned up: Velociraptor and Oviraptor from Mongolia, Unenlagia from Patagonia, and a nestling bird with a primitive, dinosaur-like head but nearly modern wings from Spain. In all, scientists count more than 100 features shared by dinosaurs and birds, among them the wishbone, air-filled skull bones and a foot with three forward-facing toes. “The anatomical similarities are overwhelming,” says Mark Norell of the American Museum of Natural History in New York. A few scientists reject the dinosaur-bird connection, viewing the similarities as having developed independently. To them, dinosaurs and birds share a common yet undiscovered ancestor but evolved along separate paths.

“But they have no physical evidence,” says paleontologist Hans-Dieter Sues of Toronto’s Royal Ontario Museum and a member of National Geographic’s Committee for Research and Exploration. “Only dinosaurs are anatomically suited to be the precursors of birds.”

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