AFP/Zhongda Zhang-IVPP
Fossil hunters in China say they have found the earliest known forerunner of the Tyrannosaurus rex, the mighty flesh-ripping dinosaur beloved of children and Hollywood.
Uncovered in Wucaiwan in the western province of Xinjiang, the species has been dubbed Guanlong wucaii, "crowned dragon of the five-coloured rocks", a reference to the tint of the earth in which it was found.
It hails from the Late Jurassic Period, around 161 million to 156 million years ago, according to the discoverers, led by Xu Xing of the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing.
By comparison, the T-rex lived much later, in the Late Cretaceous era, enjoying a 20-million-year reign of terror that ended with the extinction of the dinosaurs some 65 million years ago.
Nose to tail, T-rex measured up to 13 metres in length, whereas the best preserved of the two fossils unearthed in Wucaiwan suggest a creature that was about three metres long.
Despite these differences, the "crowned dragon" shows all the key ancestral hallmarks of the tyrannosaurids.
It shares their enlarged skull, two powerful rear feet, stubby forelimbs that end in a powerful three-fingered hand and long, blade-like teeth that suggests it too was a predator to be reckoned with.
But palaeontologist believe the "primitive" look of the pelvis also suggests something else.
It supports a theory first put forward in the 1990s that the tyrannosaurids, despite their great size, evolved from a species of swift, small-bodied dinosaurs called coelurosaurs.
Guanlong also had a highly elaborate, fragile crest, a "crown" that ran almost the entirely length of its long upper jaw.
This crest is "surprising," given that it would have surely hampered the beast in its hunt for food, the palaeontologists say.
They speculate that it was an ornament that may have been used to lure a mate or show off status. Many vertebrate species today use these tools, such as peacocks with their tails and elks with their antlers, even if the device carries a cost in movement.
Xu has earned a reputation for being the world's most successful fossil finder, unearthing extraordinary specimens that have shed light in particular on birds, spurring the theory that modern birds are the descendants of dinosaurs.
Most of his big finds have come from lake deposits in Liaoning province, in the north east of China, that are between 128 and 110 million years old.
Their study is published in Nature, the British weekly science journal.
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