(The gastric-brooding frog, Rheobatrachus silus, which swallowed its eggs, brooded its young in its stomach and gave birth through its mouth actually died out in 1983. The researchers, from the aptly named Lazarus Project, took fresh eggs from the distantly related Great Barred Frog, deactivated their nuclei and successfully replaced them with genes from the extinct frog. To date,
Similar techniques could be used to bring back the dodo, the woolly mammoth, or maybe T-Rex (the dinosaur, not the band).