Today is a sad day for Jurassic Park fans. Deep down we all knew that the prospect of cloning dinosaurs from ancient genetic material was, at best, highly unlikely. After all, the life of a DNA strandhas been estimated at only 1 million years, meaning that any solid T-Rex samples would be long gone by now. But there was always a little shred of hope that, under just the right conditions, and with the help of a wealthy benefactor, scientists might be able to create a living dinosaur just like in the movies. Sadly a group of palaeogeneticists have squashed those lingering hopes by discovering that DNA has a half-life of a mere 521 years, so even the best preserved strands break down within 6.8 million years. Since dinosaur bones are around 65 million years old, that limit is enough to end our Jurassic Park dreams.