Exam Review

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Dino discoveries

When news breaks of the discovery of a new species of dinosaur, you would be forgiven for thinking that the scientists who set out in search of the fossils are the ones who made die find. The reality tells a different story, as Cavan Scott explains.

The BBC series Planet Dinosaur used state-of-the-art computer graphics to bring to life the most impressive of those dinosaurs whose remains have been discovered in the past decade. One of these is Gigantoraptor erlianensis. Discovered in 2005. it stands more than three metres high at the hip and is the biggest bird-like dinosaur ever unearthed Yet its discoverer. Xu Xing of Beijing's Institute of Vertebrate Palaeontology and Paleoanthropology, was not even looking for it at the time. He was recording a documentary in the Gobi Desert Inner Mongolia.

'The production team were filming me and a geologist digging out what we thought were sauropod bones.' says Xu. 'when I realised the fossils were something else entirely.' Gigantoraptor, as it later became known, turned out to be an oviraptorid, a therapod with a bird-like beak. Its size was staggering. The largest oviraptorid previously discovered had been comparable in size to an emu: the majority were about as big as a turkey. Here was a creature that was probably about eight metres long, if the bone analysis was anything to go by.

Sometimes it is sheer opportunism that plays a part in the discovery of a new species. In 1999. the National Geographic Society announced that the missing link between dinosaurs and modern birds had finally been found. Named Archaeoraptor lianoingensis. the fossil in question appeared to have the head and body of a bird, with the hind legs and tail of a 124-million-year-old dromaeosaur - a family of small theropods that include the bird-like Velociraptor made famous by Jurassic Park films.

There was a good reason why the fossil looked half-bird, half-dinosaur. CT scans almost immediately proved the specimen was bogus and had been created by an industrious Chinese farmer who had glued two separate fossils together to create a profitable hoax.

But while the palaeontologists behind the announcement were wiping egg off their faces, others, including Xu were taking note. The head and body of the fake composite belonged to Yanornis martini, a primitive fish-eating bird from around 120 million years ago. The dromaeosaur tail and hind legs, however, were covered in what looked like fine proto feathers. That fossil turned out to be something special. In 2000. Xu named it Microraptor and revealed that it had probably lived in the treetops. Although it couldn't fly, its curved claws provided the first real evidence that dinosaurs could have climbed trees. Three years later. Xu and his team discovered a closely related Microraptor species which changed everything. 'Microraptor had two salient features.' Xu explains, long feathers were attached not just to its forearms but to its legs and claws. Then we noticed that these long feathers had asymmetrical vanes, a feature often associated with flight capability. This meant that we might have found a flying dinosaur.'