A FOSSIL that appears to be a bird鈥檚 body with a dinosaur tail has left some
palaeontologists with egg on their faces.
At a press conference in Washington DC last October, the National Geographic
Society heralded the fossil鈥檚 mixture of bird and dinosaur features as 鈥渁 true
missing link in the complex chain that connects dinosaurs to birds鈥�. Now it
seems that glue, not evolution, forged the link.
The fossil, named Archaeoraptor liaoningensis, came from the famous
Chinese deposits which have yielded a wealth of exquisitely preserved early
birds. Stephen Czerkas, director of the Dinosaur Museum in Blanding, Utah, had
bought it from an unidentified fossil dealer in the US. Czerkas says he spotted
鈥渁 break in contact between the base of the tail and the rest of the body鈥�, but
after analysing layering in the surrounding rock, he decided that the pieces
belonged together after all.
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This was exciting, as Archaeoraptor鈥檚 body is clearly avian, while
the straight, rigid tail is a feature of the fleet predatory dinosaurs known as
dromaeosaurs. The sizes of the bones matched, and at the time of the discovery
no one had found a dromaeosaur that small.
Since then, however, Xu Xing of the Institute for Vertebrate Paleontology and
Paleoanthropology in Beijing has found a dromaeosaur with an identical tail of
the right size in a private collection. 鈥淭here is no doubt that Archaeoraptor
is composed of a bird body and a dinosaur tail,鈥� says Xu. A CT
scan of the fossil, conducted by researchers in the US, appears to confirm that
the tail is separate from the body.
The Chinese fossils often split apart along the plane containing the bones,
producing a pair of specimens called the 鈥減art鈥� and 鈥渃ounterpart鈥�. Larry Martin,
a fossil bird expert at the University of Kansas, suspects that the Chinese
farmers who first found the fossils glued the counterpart of a dinosaur tail to
a bird fossil. 鈥淭hey found long tails attracted better prices,鈥� he suggests.
Despite having embarrassed those palaeontologists who hailed it as a missing
link, Archaeoraptor may yet prove to be an important specimen. 鈥淥nce
you cut out the dinosaur part, it probably will be an interesting bird,鈥� says
Martin, who thinks it may be one of the earliest ornithurines鈥攖he
ancestors of modern birds.
鈥淭he front half of the animal is one of a kind,鈥� agrees Czerkas. He argues
that it would have been more capable of flight than Archaeopteryx, the
oldest known bird.
However, Czerkas wants to make a side-by-side comparison of the tail on
Archaeoraptor and that of the miniature Chinese dromaeosaur before
accepting that he made a mistake. The dromaeosaur is too fragile to travel, so
that will have to wait until Czerkas makes good his promise to return the
Archaeoraptor specimen to China, perhaps in the spring.