A helicopter skims over the surface of a dark, rough sea. "I own an island off the coast off Costa Rica," says the voice of billionaire John Hammond. "I've spent the last five years setting up a kind of biological preserve." This is the trailer for one of the most successful films ever, Jurassic Park - and among the images flashed in front of our eyes is a mosquito trapped in amberFossilised resin - which is the viscous (thick, sticky) liquid inside a tree that protects it from external threats. Amber has been appreciated for its colour and natural beauty since Neolithic times..

The premiseSet-up. The basis from which a story begins. of the film - based on a novel by Michael Crichton - is that a mosquito preserved in this way is found to have sucked the blood of a dinosaur. John Hammond's team manage to isolate the DNADeoxyribonucleic acid is the material in an organism that carries genetic information. in the blood and use it to clone the creature that it came from. Unfortunately for a group of visiting scientists, the dinosaurs that result get out of control and threaten the humans.

Comparisons were inevitable when the December issue of Current Biology appeared with just such a mosquito on the cover. The amber containing it was found in Lebanon and has been dated at 125 million years old.

Scientists already knew that mosquitoes had been around far longer than humans. But they were unsure when the insects first emerged, and whether they fed on blood.

The find is important firstly because these mosquitoes are 30 million years older than any previously found. This means they belong to the Early CretaceousThe Early Cretaceous Epoch lasted from 145 million years ago to 100.5 million years ago. period, and could have had ancestors in the JurassicThe geological period between 200 and 145 million years ago when dinosaurs diversified and became the dominant land animals. period which immediately preceded it.

Secondly, they have piercing mouthparts, which suggests that they sucked blood - and could have fed on dinosaurs.

"All great science fiction must be science first and fiction second," Newsweek noted in covering Jurassic Park. According to the film's director, Steven Spielberg, it could not have been made unless cloning dinosaurs from ancient DNA were theoretically possible.

A fortnight after Jurassic Park started filming in 1992, biologists at California University announced that they had cloned DNA from a 40-million-year-old bee preserved in amber. Around the same time, a team at the Museum of Natural History in New York said that they had done the same with a 25-million-year-old termiteA small, pale soft-bodied insect that lives in large colonies..

There are problems, however. DNA is measured in units called base pairs, of which the human genomeThe complete set of genes in an organism.  contains three billion. Dinosaurs might have had as many as 10 billion - but none of the ancient DNA found in fossils contains more than 250.¹

Even if all of the base pairs needed were found, putting them together in the right order would be like sticking together a book which had been cut up into single letters.

On top of that, DNA is known to degrade over time. The oldest found so far - in the teeth of mammoths preserved by the Siberian permafrostAny ground that remains completely frozen for at least two years. Permafrost covers large regions of the Earth.  - is around one million years old.² A dinosaur's DNA would have had to survive for 65 million.

And according to Newsweek, there would be a further challenge even if scientists had a cell full of DNA: "Cells from anything but an embryo seem to have forgotten how to make the complete animal."

Yes: In recent years scientists have made extraordinary progress in extracting DNA, mapping genomes and cloning. Future discoveries could well make Jurassic Park possible.

No: Nobody has yet managed to find dinosaur DNA. Even if they did, and it had not degraded too much, they would not be able to recreate the creature as it actually was - just an approximation of it.   

Or... It would lead to disaster if it did. As one of the scientists in the film says, "Sometimes we get so preoccupied with whether we could, we don't stop to think if we should."