China

Liaoning

Information

SITE RANK

100

HABITAT Large lakes and surrounding forest

KEY SPECIES Sinosauropteryx prima, Confuciusornis sanctus, Sinosauropteryx millenni, Dilang paradoxus

TIME OF YEAR All year, but avoid during volcanic eruptions

A fossil of the earliest known bird with a toothless bill, Confuciusornis sanctus, which is thought to date from about 130 million years ago.

There are not many bird species at Liaoning. Indeed, this province in north-east China is not good birding country at all. A day’s drive from Beijing, it consists of low hills covered by farmland, together with cities and factories. The scenery is nothing special, and the environment is nothing special.

So why is it in this book? The answer lies in its rocks, and specifically in its shale deposits from 130 to 110 million years ago. Since the 1990s Liaoning has yielded some of the most important fossils ever recovered in terms of explaining the evolution of birds. The area has been described as a Mesozoic Pompeii, referring to the site in Italy where humans were famously entombed by a volcanic eruption and have been remarkably well preserved. In the few short years of its fame, with find after find being unearthed, Liaoning has cast more light on the early evolution of birds than anywhere else. Clearly, although it is a relative desert now, Liaoning was once one of the richest places on earth for birds.

The marvel at Liaoning is in the detail preserved in its fossils. There was once a shallow lake here where recently dead bodies would quickly be covered by mud and volcanic ash, with layers added from the repeated eruptions, shutting off the oxygen required for decomposition. The fine grains of sediment have allowed fossils to retain details that are missing from most other fossils elsewhere in the world, such as the soft parts of their internal organs. Some creatures have remains of their last meal still intact in their gut, while others give hints of colour patterns on the skin. And, most importantly for palaeontologists, a significant number of the fossils here have feathers.

In 1996 one discovery in particular caused a sensation. Named Sinosauropteryx prima, it was the fossil of a small bipedal dinosaur in the group known as therapods, among which is every child’s favourite, Tyrannosaurus rex. What was special about this find was that it had feathers, or at least primitive structures that resembled feathers. At any rate, its body was covered with thin, hollow filaments, yet it had no wings and was clearly a reptile, not a bird.

It was not long before another discovery added evidence to what Sinosauropteryx had hinted at. The so-called ‘Fuzzy Raptor’ Sinornithosaurus millenii, discovered in 1999, was also clearly a reptile, but its feathers were far better formed. Some of its filaments were joined together into tufts, rather like modern-day bird down, and others were joined to a central shaft, or rachis, the same structure that most feathers have today. This, in the opinion of most palaeontologists, provided conclusive evidence that feathers are not, as has been long supposed, unique to birds, but are found on fossil reptiles, too.

The implications of the finds reverberated around the palaeontological world. If therapod dinosaurs had feathers, that was pretty strong evidence that birds and dinosaurs are very closely related and, indeed, that birds could actually be little more than modified reptiles. Secondly, if non-flying reptiles have feathers, that surely would refute the idea that feathers co-evolved with the need to fly or glide? Instead, it would lend weight to the theory that feathers were initially most helpful in keeping their owners warm, and became instruments of flight only as a secondary characteristic. And thirdly, the discovery at Liaoning of Dilang paradoxus, a tyrannosaur with primitive feathers, allowed some to suggest, somewhat playfully, that perhaps the mighty Tyrannosaurus rex itself had feathers, or that its young were actually fluffy chicks.

The finds at Liaoning are not just confined to reptiles; there are indisputable birds here, too. One of the commonest is Confuciusornis sanctus, first discovered in 1994. This is a species with feathers that differ little from those of present day birds, and it was the first fossil bird found with body plumage as well as feathers on the wings or tail. Confuciusornis, dated from about 130 million years ago (the precise age is uncertain), is also the earliest known bird with a toothless bill, a forerunner of all living birds. Details of the wings show that it could fly. There are now so many fossils of this species that both males and females have been discovered; one sex, although it is not known which, had long tail feathers, which would seem to have little function except in display.

Confuciusornis and the other bird fossils from Liaoning have muddied the water somewhat in respect of the oldest known of all bird fossils, the feathered but toothed Archaeopteryx lithographica, from Germany. The specimens of this bird are dated from around 150 million years ago, but their anatomy does not suggest any close links to the therapods. Thus, the origin of birds is a matter that is still not resolved, and it is to be hoped that, eventually, all the pieces of the jigsaw can be fitted together.

The discovery of these world-famous fossils has affected the formerly obscure province of Liaoning in a number of ways. It has put it on the world map, and has also given rise to a local industry. Bird fossils are very rare and, should a farmer unearth one, the prospect of great wealth beckons. In 1999 a single specimen, thought to be a link between reptiles and birds, was bought for US$80,000; it later turned out to be a fake. This, it hardly need be said, would transform the life of a worker used to earning a few dollars a month.

Unfortunately the illegal act of digging up fossils for trade is now rampant. At first sight it seems harmless enough, but the problem is that fossils out of context (for example, removed from soil that can be dated and linked with other fossils) are devalued scientifically. The treasures of the Laioning shale could be lost, together with their secrets. Thus, by a neat irony, birds that are long extinct are now threatened by human exploitation, just as so many of their present-day relatives are.

Note the feather-like structures around the base of the tail of the fossil reptile Sinornithsaurus millenii.