Although I’m not sure if this would succeed, is is a very interesting possibility: Japanese scientists using mammoth DNA from preserved mammoth carcasses to create a half-mammoth baby inside of a female elephant. 50 years of careful breeding could result in an animal that’s 88% mammoth. However, my Future Problem Solving thought processes tell me that if this were feasible, bringing an extinct species back to life could possibly present some unforseen challenges. But for more information, see this National Geographic article.