Since Jurassic Park hit cinemas in 1993, we've all wondered if it could ever be possible. Not only would it be the coolest thing ever, but it would also represent a massive scientific achievement. But unfortunately, and it pains me to break this to some hopeful believers, there can never be a day where you can ride a dinosaur like a pony at a petting zoo. It is completely impossible, and I'm going to explain why.
A hoax article came out recently claiming that British scientists had cloned a dinosaur, which was met with a mixture of excitement and confusion by some. Let's just start by saying that the dino picture they used was apparently a baby kangaroo, not an Apatosaurus. Sorry. But that only represents a very small part of the ridiculousness of this story. The scientists apparently extracted dino DNA from a fossil in a museum of natural science. Dinosaur DNA, however, does not exist anymore. After a cell dies enzymes, water and microbes start to break down the bonds holding together DNA. This is slowed down at colder temperatures, which is why we've managed to get decent samples from frozen mammoths, but it still occurs. Scientists calculated fairly recently that DNA has a half-life of 521 years; that means it takes 521 years for half of the bonds holding DNA together to break. After another 521 years, half of those remaining bonds will have broken, etc. This will obviously vary with conditions such as temperature and the presence of microorganisms. But even if samples were preserved at cold temperatures, it was estimated that after 1.5 million years the sequences would be unreadable, and after 6.8 million years every single bond would be destroyed. Dinosaurs went extinct some 66 million years ago.
Even if, somehow, the DNA hadn't entirely degraded and there was some bits of it left, you can't just fill those bits in with DNA from another organism (like the frankenfrogosaurus implied by the film Jurassic Park). We would have no blueprint sequence available to determine what the missing bits should be filled with. Even though many modern day birds are similar to extinct dinosaurs that we might want to try to bring back (indeed, birds are avian dinosaurs), you still can't make a hybrid dinobird using their DNA. Unfortunately, biology doesn't work that way.
It doesn't end there. Even if we did miraculously manage to find some usable dino DNA, we still wouldn't be able to do anything with it. The scientists apparently implanted the dino DNA into an ostrich womb (?). I can only assume they meant egg cell, as injecting DNA into the womb of an animal won't magically make an embryo. When cloning animals, scientists need to replace the genetic material from a donor cell of an animal that they are trying to clone. We don't have any spare viable dinosaur cells hanging around. Scientists are hoping to be able to use elephant cells (if they decide it is ethical) to clone wooly mammoths, but even this requires some re-jigging of the normal cloning process since these two species diverged a long time ago. You couldn't replace DNA in a donor ostrich cell with, say, stegosaurus DNA to make a viable cell, they're too different. Apatosaurus's were also huge- the developing foetus would simply be too big for the ostrich.
To carry on with this string of poo pooing, nuclear DNA is also not the only DNA found in cells. Your cells also contain little sausage-shaped energy making factories called mitochondria which possess their own mitochondrial DNA. Researchers claimed that because of this, Dolly the sheep (the first cloned mammal) was not quite a true clone. It's very likely that mixing, say, ostrich mitochondria with (if it existed) dinosaur nuclear DNA would result in incompatibility problems.
In sum, unfortunately we are never going to experience a real life Jurassic Park. But this might be a good thing, if we are to learn anything from films... It would probably be a disaster.