Scientists have extracted and decoded the DNA of a cave bear that died 40,000 years ago. They plan to unravel the DNA of other extinct species, including our closest ancient relatives, the Neanderthals. But they say the idea of obtaining DNA from dinosaurs, depicted in the film Jurassic Park, remains science fiction. It is highly unlikely that viable genetic material will ever be recovered from fossils that are hundreds of millions of years old. But the scientists hope to be able to sequence the DNA of ancient humans, which lived at the same time as cave bears, raising the prospect...