The idea that dinosaurs were the ancestors of birds may sound a little strange, but there is growing scientific evidence that this may be the case. "Not the big dinosaurs like a tryannosaur or brachiosaur but the turkey-sized dinosaurs like compsognathus, which ran free on most of the earth's plains for 140 million years just like their larger and easier recognized cousins.
"I think it's now safe to say that the oldest known bird in the fossil record in archeoptryx," Yale University's Dr. John H. Ostrom said at a news conference during the annual meeting of the American Association for the Advancement of Science held here this week.
"There is strong evidence that it had feathers and even stronger evidence that it had a skeleton that was almost indistinguishable from small dinosaurs," he said.
There are five preserved fossil specimens of archeoptryx, a turkey-sized creature that thrived 150 million years ago in the age of the dinosaur. Most scientists called the creature a dinosaur, but at least three of the five specimens have strong impressions of feathers. None had wings for powered flight, but there are indications that they could have flown like hens or roosters for short distances.
Ostrom has a deep interest in archeoptryx since eight years ago, when he identified a specimen in a Dutch museum that for 20 years had been classified as a pterosaur, which is little more than a flying reptitle and hardly an ancestor of the bird.
The pterosaur is known for its weak, painfully thin and short hind limbs. This pteorsaur had robust hind limbs. The pterosaur also has four fingers on each hand, three stubby ones of the same size and the fourth much longer which it used to support its wings. The pterosaur in the Dutch museum had only three fingers, all of varying lengths, like archeoptryx.
"It took me 15 to 20 seconds to make the identification," Ostrom remembered yesterday. "Tha was no pterosaur, that was archeoptryx." Ostrom claims no credit for the idea that dinosaurs gave birth to the bird. The Yale professor gives that credit to British evolutionist Thomas Huxley, who first made the connection in 1868.
But in 1926, Danish zoologist Gerhart Heilman wroter in his book, "The Origin of Birds," that birds had no ties to dinosaurs and that "put the lid on" the connection for 40 more years.
In 1970, Ostrom took the lid off when he identified the specimen in the Dutch museum. He's joined today by a growing number of evolutionists, including Dr. Robert Bakker of Johns Hopkins University and the Smithsonian Institution's Nicholas Hotton, who said yesterday: "There is still some question about whether dinosaurs were warm-blooded or cold-blooded, but I believe that the dinosaurs that became warm-blooded were the ones that became birds."
The oldest known flying bird was ichthyornis, which lived about 30 million years after archeoptryx, and had teeth, unlike the birds we know today.Why did it have teeth? Ostrom can only speculate, but says he thinks tht birds lost their teeth when they improved their plumage and beaks to preen themselves.
What Ostrom wants to find is the missing link between ichthyornis and archeoptryx, hopefully a specimen with definitive feathers and more developed shoulders that would more strongly suggest the muscles used for powered flight.
Why is it all important? Because birds have some of the most exquisite internal metabolic mechanisms known to zoology and because birds are unique in the animal kingdom.
"Birds are perhaps the most ingenious manifestation of evolution we know," Ostrom said. "Their legs are beautifully designed for running, and developed both independently. We'd like to know how and we'd like to know why."