Thursday 28 December, 2000
The Feathered Dinosaurs of Liaoning
Is it possible that Tyrannosaurus Rex hatched cute, fluffy chicks?
In the final journey of Discovery, series producer Martin Redfern, travels to the Liaoning Province where fossil evidence has been unearthed to suggest that dinosaurs grew feathers and flew with the birds.
Sihetun
Slowly but smoothly the night train glided north east from Beijing into Liaoning Province. By six am we had reached the bustling city of Jinzhou from where we continued on a white-knuckle taxi ride. My guide was Dr Zhou Zhonghe from the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing. He is a rarity among bright young Chinese scientists in that he has returned home after completing his PhD in the USA. What lured him back were not the overnight train rides or the bumpy roads but the fantastic fossils that are being uncovered in the hills of Liaoning.
We drove between parched brown fields and passed low mud brick farms, the dirt road carrying little traffic not pulled by donkeys. An icy wind blew from Siberia to the north and the farmers buttoned up their coats against it as they gathered every last scrap of vegetation in the hope they can keep their donkeys alive through another winter.
As we came in to the little village of Sihetun however, there was a subtle difference. There were a few modern villa style homes and some of the young men were riding new Japanese motorbikes. Clearly there was an additional source of income here. We found it on the hillside just behind the village. What looked like a huge quarry had been dug out of the hillside but this was not a gold rush: the site has yielded some of the most exciting fossils ever discovered, the skeletons of dinosaurs with feathers.
| ‘There are so many different creatures of various sizes ranging from pigeon to pony covered with plumage ranging from fluff to feather.’ | |
Dromeosaurs
The fossils have been dated to 124 million years ago, in the lower Cretaceous period. At that time there was a shallow lake here and anything that fell into it soon got buried under mud and volcanic ash, so many of the skeletons are preserved intact. The fine shales even preserve traces of their feathers. More than 1,000 specimens have been discovered here, and in the surrounding region, and they provide strong evidence of an evolutionary link between dinosaurs and birds.
But the story is not simple, not least because there are so many different creatures of various sizes ranging from pigeon to pony covered with plumage ranging from fluff to feather. Most of them seem to belong to the group of dinosaurs called dromeosaurs. These are the little fast-moving creatures such as Velociraptor, made famous by the film Jurassic Park. They in turn belong to the larger group known as theropods, which includes the mighty carnivore Tyrannosaurus Rex.
The most dinosaur-like examples were clearly too heavy to fly and their feathers were too small and primitive. One species, called Sinosauropterix, has only a faint fuzz of fibres around its body; it may be downy feathers though others suggest it could have been hair or flaps of skin.
But Zhou Zhonghe points out that the smaller a dinosaur was, the harder it would have been for it to control its body temperature so maybe the first feathers were developed for thermal insulation and later for display. Some have suggested that larger relatives were warm blooded and that their babies would have benefited from insulating down. It is strange to think that the terrible T Rex may have hatched cute, fluffy chicks!
Confuciusornis
There are plenty of fossils from Liaoning of creatures that clearly could fly. One species, named Confuciusornis, has been found in large numbers and is very bird-like with big quailed flight feathers and a beak.
The palaeontologists are searching hard to find missing links between birds and dinosaurs. In 1999 they thought they had one. It was purchased in the USA for $80, 000 dollars from a dealer. A small fraction of that money had probably helped to buy a Chinese farmer a motorbike before the fossil was smuggled out of the country. The export of vertebrate fossils from China is illegal but some of the local officials who are meant to enforce the law seem to have acquired fine specimens themselves.
Archaeoraptor
The supposed ‘missing link’ was named Archaeoraptor and was featured as the cover story in National Geographic magazine. But it was soon found to be a fake, a composite of a bird-like creature with the tail of a more primitive theropod dinosaur. When a layered rock is split open to reveal a fossil, you're left with two halves, part and counterpart and the breakthrough in this story came when Xu Xing of the Institute of Vertebrate Palaeontology was able to purchase, for a mere $5000, the counterpart of the tail stuck onto Archaeoraptor. With it came the animal that really belonged to the tail and it was the smallest theropod dinosaur ever found. It was named Microraptor and was published in the journal Nature in December 2000.
About the size of the pigeon, it too had feathers. It had relatively powerful long legs and might have been able to fly with a good run up on the ground. But it is more likely that it was a tree climber. It has the sort of curved, pointed claws on its feathered forelimbs or wings that are seen in things like woodpeckers and squirrels which climb tree trunks. One toe on each hind leg is pointed back as in birds, for perching. Maybe it could launch itself from the branches and at least glide if not fly.
Disputed dinosaurs
There are still those who dispute hotly that theropod dinosaurs gave rise to birds and they have one undeniable piece of evidence in their favour. The oldest known birds, Archaeopteryx, from Germany, are 26 million years older than the feathered theropods from Liaoning, so the latter could not have been their ancestors. Zhou Zhonghe’s PhD supervisor in Kansas, Professor Larry Martin, disagrees with his student and thinks that birds and dinosaurs had a common ancestor far further back in the geological record.
But for most fossil experts, the evidence is clear. The feathered dinosaurs of Liaoning have many features in common with birds and not only feathers. They have a primitive wishbone, the bone in the chest that braces the body against the flight muscles in birds. And they have a characteristic half-moon shaped bone in their wrists, which enables birds to flap their wings wide. The debate is bound to continue but the number and quality of fossils still being discovered in Liaoning means that there will be plenty more evidence.
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| Life Story |
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In Life Story, Martin Redfern, travels the world in search of fossils that record key events in the history of life.
The story starts in Australia and Namibia where microscopic algae were suddenly joined by giant worms and creatures that looked like floating airbeds. Soon afterwards, preserved traces found in China and Canada revealed the ancestors of most modern groups of animal, including something looking like an animated anchovy fillet.
The journey then moves on to a black lagoon, out of which crawled some of the first ever four-legged creatures, and up, as dinosaurs grew feathers, to fly with the birds.
To follow this incredible journey, click on the links below. |
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