Cloning

Sorry, you will never ride, see or pet a cloned dinosaur 

It’s been years since cloned animals first appeared, so why aren’t we able to reach back to the Cretaceous yet? Well, this isn’t just a question of improving our current cloning methods. We lack the fundamental materials to clone anything from 65 million years ago. Taking into account the influence of Hollywood, you could be forgiven for thinking that dinosaur blood is flowing like rivers in labs all over the world. The fact is, we don’t have dino DNA.
We also lack an intact dino nucleus to take up residence in a cell. You can’t grow a dinosaur with just a pile of DNA.

http://www.extremetech.com/extreme/133802-sorry-you-will-never-ride-see-or-pet-a-cloned-dinosaur

DNA has a 521-year half-life 

Few researchers have given credence to claims that samples of dinosaur DNA have survived to the present day, but no one knew just how long it would take for genetic material to fall apart. Now, a study of fossils found in New Zealand is laying the matter to rest — and putting an end to hopes of cloning a Tyrannosaurus rex.
By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.
“This confirms the widely held suspicion that claims of DNA from dinosaurs and ancient insects trapped in amber are incorrect,” says Simon Ho, a computational evolutionary biologist at the University of Sydney in Australia. However, although 6.8 million years is nowhere near the age of a dinosaur bone — which would be at least 65 million years old — “We might be able to break the record for the oldest authentic DNA sequence, which currently stands at about half a million years,” says Ho.

http://www.nature.com/news/dna-has-a-521-year-half-life-1.11555