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Thursday, October 8, 1998 Published at 19:14 GMT 20:14 UK


Birds of a feather

If you the film Jurassic Park frightened you about recreating dinosaurs through genetic engineering, then your worst fears could well be confirmed.

Watch a computerised animation of the evolution of the dinosaur to bird
As the debate in the natural history world concerning the link in origin between the dinosaur and the bird rages on, scientists at the University of Connecticut have taken the relationship one step further, according to the BBC's Horizon programme.

They are currently researching the possibility of switching off the various genes, which currently make up a bird, to re-create a living dinosaur.

They have already managed to remove the beak gene in the embryo of a chick to replace it with the tissue of another animal that produces dentine, the essential ingredient of all the teeth.

[ image: Inserting new tissue into a chick embryo]
Inserting new tissue into a chick embryo
So far, scientists have only been able to create an individual tooth, but research shows that in principle, they could "de-bird" a bird, giving it a full jaw of teeth, like that belonging to the dinosaur.

The possibilities seem endless. Take out the feather genes and replace them with ones for scales, and take out the wing genes and put in the necessary ones for arms - a small, predatory dinosaur has been made.

But before the Royal Society for the Protection of Birds decides to change its name, and before people contemplate putting protective roofs on their homes, scientists say they are not contemplating any re-creation of the prehistoric giant.

William Upholt from Connecticut University's School of Dental Medicine says: "The results of these experiments may eventually be useful for tooth regeneration for people who have lost their tooth through disease or accidents, or people who have no teeth at all."

New beginnings

Scientific discussions and research on the origin of birds from dinosaurs have also entered a new phase in the past few months.

Recent fossil finds in north-eastern China have amazed paleontologists and ornithologists as they seem to confirm the dinosaur at least as a primitive, clumsy version of birds as we recognise them today.

[ image: John Ostrom: Making the natural world sit up and listen]
John Ostrom: Making the natural world sit up and listen
Scientist John Ostrom from Yale University has been waiting for this day for 30 years, during which he has assiduously studied and compared the skeletons of dinosaurs and birds and concluded startling similarities.

"I'm so excited by the developments in China that I can't talk about it enough. The discoveries show that there is a whole new chapter of theological time preserved in China," says Mr Ostrom.

His theory is simple. Over millions of years, a small predatory dinosaur developed into a feathered dinosaur, which over yet more time acquired the ability to fly. Finally, after more millions of years, predatory birds developed into the modern ones we see today.

An age-old story

This year, farmers in the north-east region of China were found to have been excavating hundreds of fossils every day.

Contrary to local belief that these were the remains of ancient dragons, they turned out to be some of the best-preserved fossils in the world, surviving for more than hundreds of millions of years.

[ image: Contrary to popular belief, some dinosaurs were no bigger than a turkey]
Contrary to popular belief, some dinosaurs were no bigger than a turkey
The fossils, apart from their exquisite beauty, gave new impetus to Mr Ostrom's theories and provided the essential missing link in the origin of birds.

One of the fossils turned out to have the anatomy of a dinosaur with what appeared to be a fringe of feathers running down its back. Could it really be a feathered dinosaur?

An animated portrait of the Caudipteryx
And since its discovery, other feathered dinosaurs have been found in China - the latest named "feathered tail" or Caudipteryx.

Their appearance sent shockwaves through the natural history world.

Prior to this, the only other "real" evidence of the link between birds and dinosaurs had been Archaeopteryx, also a fossil of a feathered dinosaur found by German scientists 100 years ago.

[ image: How could this creature....]
How could this creature....
But one of Mr Ostrom's staunchest opponents, Alan Feduccia, an ornithologist at the University of North Carolina, stands firm.

He says birds evolved long before dinosaurs came along. They descended from much more primitive reptiles, and any similarities, such as they both walk on their hind legs, are coincidental. He calls it convergent evolution.

Mr Feduccia says: "One of the most examples of convergence are the ancient fish reptiles and dolphins. They are superficially almost identical, but when one looks at the structure in detail, the similarities fall down."

The heights of evolution

Researchers from the American Museum of Natural History in New York, concluded that Caudipteryx and the other fossils were undeniably feathered dinosaurs, but they were not able to fly.

[ image: be the descendant of this?]
be the descendant of this?
If Caudipteryx was to be the missing link between dinosaurs and birds, how did its descendants ever get off the ground?

According to Mr Ostrom, the bird's flexible arm and wrist which enable it to flap its wings up to 12 times a second, were nevertheless inherited from Caudipteryx and Archaeopteryx.

Watch Archaeopteryx take to flight
The former had the same distinctive wrist as the modern-day bird, and the latter used this wrist to flap its wings to carry out a primitive type of flying, like cruising for moderate distances.

Biologist Jeremy Rayner from Bristol University says: "The difficult thing for a bird is taking off and landing, hovering, changing flight direction, escaping predators, all these things, I don't think Archaeopteryx could do.

[ image: Learning to fly]
Learning to fly
"I think probably it was quite a clumsy flier."

For the moment, Mr Ostrom's theories have been vindicated, thanks to the positive response of the natural history world to the discovery of the fossils from China.

And if some of the genetic possibilities are pursued to their full impact, the feathered dinosaur or the toothed bird could no longer be a creature belonging only to the most bizarre of sci-films.

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