To ‘de-extinct’ an animal, you need a source of the animal’s DNA, which provides the blueprint for making it. DNA is sometimes preserved in fossils, and the oldest DNA extracted to date comes from a 700,000-year-old horse bone found in the Canadian permafrost.
However, DNA breaks down over time, and scientists think that it’s unlikely to be found in any specimen older than a million years. Dinosaurs went extinct 65 million years ago. No dinosaur DNA, no dinosaurs. Sorry!
Some other species, however, are fair game. In 2003, scientists briefly de-extincted a type of goat, called the bucardo. DNA-laden cells, taken from the last living female before she died, were used to create a clone, and the resulting embryo was transplanted into the womb of a living domestic goat.
The bucardo was delivered by Caesarean section, but died shortly after birth due to lung defects. The bucardo was therefore the first animal to be de-extincted, but also the first animal to go extinct twice!
Other de-extinction projects include attempts to revive an Australian amphibian called the gastric-brooding frog, a North American bird called the passenger pigeon and the one and only woolly mammoth. These use a combination of cloning, gene-editing and stem cell methods, but don’t hold your breath waiting for the pitter-patter of tiny feet. De-extinction is still very much in its infancy, so for now, take solace in the fact that dinosaurs never really left us. Birds are their direct descendants, and they’re everywhere.