While not all scientists agree, many consider Archaeopteryx the first bird, since it had wings and was the first fossil found with feathers.
Details have been lacking on the animals, however, since only a few fossil specimens have been found. The new one, reported in Friday's issue of the journal Science, is the 10th known and one of the most complete.
Contrary to what had been thought, the new fossil shows that the first toe was not reversed in Archaeopteryx, as is the case on current birds, according to a team led by Gerald Mayr of Research Institute Schenkenberg in Frankfurt, Germany.
Lack of the reversed toe would hamper the animal's ability to perch like current birds, the researchers said.
On the other hand, its second toe could be extended, like those of theropod — beast-footed — dinosaurs, a group that included such well known examples as T. rex.
Archaeopteryx was considerably smaller, however, close to the size of a magpie. The new example lived about 150 million years ago in what is now Bavaria.
Matthew T. Carrano, a dinosaur expert at the Smithsonian's National Museum of Natural History, agreed that the discovery supports those who consider birds descendants of dinosaurs.
The lack of a reversed toe doesn't mean an Archaeopteryx couldn't sit in a tree, but probably indicates that it was not a habitually tree-living animal, said Carrano, who was not part of Mayr's team.
"We assume it could fly but we don't have a lot of information about its flying ability," he added.
Most of the known specimens are partial so the new one adds to the knowledge of the animals, Carrano said.
Archaeopteryx was originally identified as the earliest fossil bird because of its feathers, Carrano said. Since then other dinosaurs with feathers have been found; if Archaeopteryx were discovered today it probably would be considered more dinosaur than bird, he said.
But while the new discovery shows that Archaeopteryx was less birdlike than had been thought, he added, there were a lot of intermediate steps between dinosaurs and birds and this was one of them.
The specimen, discovered in the Solnhofen area of Germany, was acquired by the Wyoming Dinosaur Center in Thermopolis, Wyo.