Tyrannosaurs get a father figure - Nature

http://www.nature.com/news/2006/060206/full/060206-5.html

Fossil hunters find the first Jurassic specimen of this fearsome family.
Michael Hopkin


Ask any dinner-party palaeontologist and they'll tell you that, despite its star turn in Jurassic Park, Tyrannosaurus rex didn't live in the Jurassic period. But now a team in China has found a tyrannousaur that did, and it gives us valuable clues about the rise of this clan of prehistoric predators.

The new species, found in Xinjiang province in northwestern China, lived around 160 million years ago. This makes it more than twice as old as T. rex, and the most primitive known member of the family.

At just 3 metres long, the creature is a small relative of T. rex, which could reach a mighty 13 metres. But its gaping, beak-like face armed with teeth, and its powerful legs, show that it too would have been a ferocious killer.

The dinosaur's discoverers, led by Xing Xu of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, have named it Guanlong wucaii - meaning 'crested dragon from the five colours'. The name comes from the huge nasal crest on the creature's head, and the fact that it was found in a region of China characterized by many-coloured rocks. The team describes the find in this week's Nature1.

Rare vintage

Dinosaur specimens of this vintage are rare, says Mark Norell, who is based at the American Museum of Natural History in New York and is part of the team who studied the find. Most other Jurassic dinosaur fossils have been unearthed in the Americas. "This fills in a big blank about tyrannosaurs," he says. "With samples from only one continent, you don't have a good picture."

The presence of a nasal crest is particularly interesting, says Norell, because it is so similar to the head ornaments carried by many of today's birds. Both birds and carnivorous dinosaurs such as tyrannosaurs belong to the evolutionary family known as the theropods.

The crest of G. wucaii probably functioned as a signal, either to attract potential mates or for species recognition. "It would not have been used for fighting - it would have been paper-thin," Norell says.

If it was a sexual ornament, it might imply that this individual was a male. But if it was for species recognition, that would leave the dinosaur's sex in the balance, and determining sex using bones alone is tricky. "That's still a long way ahead," says Norell.

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