Many of today's paleontologists say birds are dinosaurs—specifically, the surviving members of a group called theropods. But is it true? Alan Feduccia, an ornithologist and evolutionary biologist at the University of North Carolina at Chapel Hill, doesn't think so. He and a handful of other skeptics argue that birds evolved from an early dinosaur ancestor, making them only slightly closer relatives of T. rex than lizards are. Feduccia shared his views with Discover associate editor Kathy A. Svitil.
Why don't you think birds are descended from dinosaurs?
First, the time line is all wrong. These alleged dinosaurian ancestors of birds occur 25 million to 80 million years after Archaeopteryx, the earliest known bird. Second, by the time you get to dinosaurs, you are dealing with fairly large, earthbound creatures, which means they would have had to evolve flight from the ground up, rather than from the trees down. Evolving flight from the ground up is biophysically implausible.
Third, many of the features of birds and dinosaurs—the hands and teeth for example—don't match. The theropod dinosaur hand consists of the thumb and the next two fingers. The bird hand is made up of the middle three fingers. You can't just flip a switch to go from one type of hand to the other. Of course, it doesn't matter what line of evidence you come up with, you are automatically wrong if it is anything contrary to the dinosaurian origins of birds.
What do you think the first birds were like?
I envision a hypothetical proto-bird as a rather small, arboreal creature, the size of a small lizard and weighing less than a couple of pounds, with feathers or proto-feathers. It would have used all four legs to jump from branch to branch and parachute, and then began gliding and active flight.
Some recent dinosaur fossils from China have a downy, featherlike covering. Doesn't that prove a link between dinosaurs and birds?
People have accepted that these filamentous structures—dino fuzz—represent proto-feathers. But these things do not resemble feathers, and I don't think they have anything to do with feathers. To me, they look like preserved skin fibers.
The difference between feathers and scales is very, very small. You can transform bird scutes [the scales on bird feet] into feathers with the application of bone morphogenic protein. So while people imagining models for the evolution of feathers feel that filaments must be an intermediate step between scales and feathers, you really don't need that stage.
What about all the other evidence for feathered dinosaurs?
When we see actual feathers preserved on specimens, we need to carefully determine if we are looking at secondarily flightless birds that have retained feathers and only superficially resemble dinosaurs, or if the specimens are in fact related to dinosaurs. That's a difficult issue to deal with right now, given the existence of fake fossils.
So far, only one feathered dinosaur, Archaeoraptor, has been publicly acknowledged as a forgery. You think there are others?
Archaeoraptor is just the tip of the iceberg. There are scores of fake fossils out there, and they have cast a dark shadow over the whole field. When you go to these fossil shows, it's difficult to tell which ones are faked and which ones are not. I have heard that there is a fake-fossil factory in northeastern China, in Liaoning Province, near the deposits where many of these recent alleged feathered dinosaurs were found.
Journals like Nature don't require specimens to be authenticated, and the specimens immediately end up back in China, so nobody can examine them. They may be miraculous discoveries, they may be missing links as they are claimed, but there is no way to authenticate any of this stuff.
Why would anyone fake a fossil?
Money. The Chinese fossil trade has become a big business. These fossil forgeries have been sold on the black market for years now, for huge sums of money. Anyone who can produce a good fake stands to profit.
If there are good reasons to be skeptical, why are you perceived as being on the scientific fringe?
The idea of being able to watch living dinosaurs by looking out at the birds in your backyard bird feeder is very appealing. The popular press naturally jumped all over it. It's also a money game. Many museums have promoted the idea of birds being living dinosaurs, and they have spent huge amounts of money on exhibits about that link. Plus, some paleontologists have spent three decades saying that birds evolved from dinosaurs, so there are careers at stake. On the other hand, there is an army of people out there who do not buy into it. We are just not as vocal as the other side.
Is there anything that would convince you birds really did evolve from dinosaurs?
At the time period when birds are thought to have evolved, there are plenty of theropod dinosaurs, but they do not have the key birdlike features. Finding a feathered dinosaur that lived earlier, during the late Triassic, would be very convincing. Until we discover the critical specimens, the issue will never be laid to rest.
How did you get involved in the debate in the first place?
I really was not interested in the origin of birds until I wrote a book called The Age of Birds back in 1980, for which I had to write a chapter on bird origins. I tried to be as fair as possible, but when I did not come down firmly on the side of the dinosaurian origin of birds, I was viewed as a heretic. The vitriolic response I got was a big red flag to me. If these researchers were so convinced that they were right, why did it make a difference what I thought? Why did they get so enraged? As the years progressed, I started looking into the problem of the origin of birds in great detail, and everywhere I looked, it was as if we were being asked to put a square peg in a round hole.
How did flight evolve in the vertebrates?
Almost every group of vertebrates has members that evolved flight--reptiles, amphibians, mammals, and of course birds. As we go through the groups, the one thing that really stands out is that they all evolved flight from the trees down, by taking advantage of the cheap energy provided by high places, namely gravity. So you have two prerequisites for the origin of flight, small size and high places, and then it's really easy to evolve flight. There's nothing to it. Energetically, the cheapest way to traverse the forest is to climb and glide, climb and glide, climb and glide.
Why should we care about how birds have evolved?
Understanding vertebrate history is integral to understanding the history of life on Earth and our own position among Earth's fauna. We can never understand how we evolve unless we understand how the animals of the Earth evolved.
What are some other important issues in evolution today?
Another area of tremendous controversy concerns the evolution of modern bird orders. The classic view has been that modern bird orders, ducks and all these modern birds, evolved over 100 million years ago before the breakup of the continents. My view is that the event that caused the extinction of the dinosaurs 65 million years ago was also devastating for birds, but that they evolved explosively following the extinctions, just like the major groups of mammals.
This brings up one of the major questions in vertebrate history and evolution in general: Does the evolution of populations occur in very sudden spurts or as a result of the gradual accumulation of small changes over long, long periods of geologic time?
Where do you think birds will evolve from here?
The world's biodiversity is being destroyed at such an astonishing rate right now that there may not be much left 30 years from now. But hopefully, we'll be able to do something about this problem.
Were you ever into dinosaurs as a kid?
Yeah, I loved dinosaurs. When I was growing up, I also had a large collection of turtles and snakes and an affinity for animals in general. But you can't study dinosaurs directly, so birds were a good second.
Creationists have used the bird-dinosaur dispute to cast doubt on evolution entirely. How do you feel about that?
Creationists are going to distort whatever arguments come up, and they've put me in company with luminaries like Stephen Jay Gould, so it doesn't bother me a bit. Archaeopteryx is half reptile and half bird any way you cut the deck, and so it is a Rosetta stone for evolution, whether it is related to dinosaurs or not. These creationists are confusing an argument about minor details of evolution with the indisputable fact of evolution: Animals and plants have been changing. The corn in Mexico, originally the size of the head of a wheat plant, has no resemblance to modern-day corn. If that's not evolution in action, I do not know what is.