De-extinction is fascinating but controversial. On the one hand it's needlessly cruel to animals, it threatens to disrupt natural habitats, and it's extremely expensive and the money could have been used for conservation. On the other hand...who wouldn't want to see a woolly mammoth?! There's an upper limit to how old a sample can be for us to be able to recover enough intact DNA for de-extinction; current estimates put that at somewhere along the lines of 1.5 million years. All the coolest stuff died long beore then. Recently, the minimal genome project created a synthetic organism with a record small 473-gene genome. It's got no genetic redundancy, and it needs every single one of those genes to survive. In nature, the smallest is a bacteria called Microplasma genitalium with 525 genes. Even other simple microorganisms usually have thousands; E. coli has ~4500. Of those 473 essential genes, nobody knows what 149 of them do. We don't know the function of 1/3 of the genes essential to the most basic form of life that we know of. Once we understand more completely how life works, we can start designing new life. We already have the tools, and they'e getting better all the time. At some point, it won't matter that there's no more cloneable dino DNA left on earth; we'll be able to design a genome for an organism that looks the way we think a dinosaur should. We're obviously a long ways off, but the dream is still pretty cool. I should write a post-apocalyptic sci-fi book with genetically engineered dinosaurs! Interested, Tom?