Despite the great birdosaur fiasco, birds are still dinosaurs

I was forced to learn to spell archaeopteryx in 1989, when my daughter Nikki came home from first grade at Meremac School reciting “A-R-C-H-A-E-O-P-T-E-R-Y-X.” Her class was just starting to learn to spell, and the teacher assigned them that word right off the bat. “If you can spell archaeopteryx,” she told them, “you can spell anything.” Every kid in that class learned how to spell archaeopteryx, and, in doing so, felt they could learn anything they set their mind to. Good teacher.

Archaeopteryx (pronounced “archie-op-ter-ichs”) is the first bird for which we have clear fossil evidence. About the size of a crow, the first fossil was found in a Jurassic limestone quarry in Bavaria in 1861. It had the clawed fingers and long bony tail of a dinosaur, with the wishbone and feathered wings of a bird.

For more than a century people have argued about archaeopteryx. Did archaeopteryx evolve from a dinosaur, or from some other reptile? It is difficult for a non-paleontologist to appreciate the heat with which this seemingly dry question has been, and is being, argued.

Boiling more than a century of ferocious argument down to a few lines, the preponderance of evidence favors a dinosaur ancestor. Archaeopteryx is remarkably like a therapod dinosaur called velociraptor. You may remember velociraptors as the scary guys that stalked the kids in the kitchen in the film JURASSIC PARK. Like velociraptor, archaeopteryx has an unusual swivel-jointed wrist, a long, very deep shoulder blade, a fused collar bone (familiar as the “wishbone” of Thanksgiving turkeys), and many other shared features.

As in all good scientific fights, evidence hasn’t discouraged dispute. Despite a mountain of evidence that birds evolved from dinosaurs, a few scientists I will call the die-hards still refuse to accept this conclusion. Even in today’s issue of SCIENCE there’s an article by several of the die-hards, arguing the case against the dinosaur-bird link. Its guys like these that make science fun.

What should have been the final nail in the die-hards’ coffin, the “smoking gun” proof of a dinosaur-bird direct link, was the discovery in 1996 in China of dinosaurs with feathers. The first of these, called sinosauropteryx, has no wings, but is covered with a light feather-like fuzz. A dinosaur with a feather coat.

“Not really feathers,” object the die-hards, “Just fuzz.”

Then, last year, there was a report from the same Chinese fossil beds of a dinosaur with real feathers and bird-like wings. The remarkable fossil was purchased at a fossil show by a dinosaur artist named Stephen Czerkas, who named it Archaeoraptor. The paper he wrote describing it was turned down by SCIENCE and NATURE, two major scientific journals, but NATIONAL GEOGRAPHIC went on to publish an article about it in November, 1999. I wrote a column about it that same week. The birdosaur, newspaper reports called it, the missing link between dinosaurs and birds.

The birdosaur turned out to be a hoax, however. The glued-together rock slab is a composite, containing the body of a bird and the tail of a velociraptor-like dinosaur. How was the fake uncovered? Like the two slices of bread on a turkey sandwich, this fossil has two “halves” of rock sandwiching the fossil itself. Czerkas had one piece of bread and the turkey meat. A Chinese farmer came forth with the other piece of bread, a slab containing the impression of the dinosaur tail — along with the rest of the dinosaur, and no bird.

“Knew it!” crowed the die-hards.

But out of the rubble of the birdosaur fiasco, other very exciting fossils have come to light from the same Chinese fossil fields, and they are not fakes. Called Caudipteryx (that’s “caw-dip-ter-ichs”), Greek for “tail feathers,” the fossil dinosaur has large feathers on its tail and arms. Two were discovered in 1998, and a third beautifully preserved specimen was reported this month at the 5th International Meeting of the Society of Avian Paleontology held in Beijing, China.

If it has feathers, it must just be some kind of bird we don’t know much about,” object the die-hards.

Paleontologists disagree. While Caudipteryx has a handful of bird-like features, including feathers, it has many features of velociraptor dinosaurs, including short arms, serrated teeth, a velociraptor-like pelvis, and a bony bar behind the eye. Paleontologists who have studied the new fossils describe Caudipteryx as sitting on a branch of the dinosaur family tree between Velociraptor and Archaeopteryx.

It seems feathers are not a distinguishing trait of birds. They first evolved among the dinosaurs. Because the arms of Caudipteryx were two short to use as wings, feathers probably didn’t evolve for flight. Instead, they probably served as insulation, much as fur does for mammals. Flight is something that certain kinds of dinosaurs achieved as they evolved longer arms. We call these dinosaurs birds.

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