Dinosaurs from DNA?

Insect preserved in amber, Oligocene, Baltic region. Source: Museum Victoria.

Can ancient DNA be used to bring dinosaurs back to life?

In Jurassic Park and its sequel, The Lost World, dinosaurs were re-created from fragments of DNA found in the stomachs of bloodsucking insects encased in amber. In 1995, science moved one step closer to fantasy with reports of ancient DNA being extracted from 80 million year old dinosaur bones. But how close did they get to recreating a dinosaur?

The scientists attempted to isolate ten small fragments of DNA. After many attempts they successfully isolated just one fragment, 174 base-pairs in length, from a gene known as cytochrome-b. This fragment represents a tiny portion of the roughly 3 billion base-pairs of DNA which would comprise the entire genetic code of a dinosaur.

The scientists then attempted to replicate (or copy) the tiny DNA fragment. In nine attempts they obtained nine slightly different copies of the DNA fragment. So which, if any, of these nine fragments contained the correct genetic code?

None. All the DNA fragments were eventually identified as an unusual form of the human cytochrome-b gene known as a pseudogene. Pseudogenes occur when a gene is accidentally duplicated and the copy inserted into a different part of the genome. As the pseudogene is non-functional, its DNA sequence changes and eventually looks quite different from that of the real gene.

The reality falls far short of the spectacular hopes inspired by the movie 'Jurassic Park'.