A 1,100-pound teenage mammoth, which scientists believe may have been killed by a hunter on a summer day thousands of years ago, was excavated on the North Siberian Taimyr peninsula in late September. The mammoth, named Jenya, after the 11-year-old Russian boy who discovered its legs protruding from the frozen mud, is one of the best-preserved specimens ever found. But its DNA has been damaged by low temperatures, making Jenya unsuitable for cloning, said Professor Alexei Tikhonov of the Zoology Institute in St. Petersburg, who announced the findings.