South African palaeontologist Adam Yates attends a news conference in Johannesburg November 11 ,2009. A huge dinosaur discovered in South Africa is a previously unknown species that sheds light on the evolution of the largest creatures ever to walk the earth, Yates said on Wednesday. Yates, a palaeontologist at Johannesburg's Wits University, said the seven-metre-long Aardonyx Celestae occupied a "very significant position in the family tree of dinosaurs". REUTERS/Stringer (SOUTH AFRICA ANIMALS ENVIRONMENT)
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