Excavated mastodon bones, Alaska, USA. Mastodons were tusked elephant-like mammals that inhabited North America, Asia and Europe from 34 million years ago. They went extinct at the end of the last Ice Age some 11,000 years ago. Bones of these animals were preserved and fossilised in the tundra of Arctic regions. This photograph, originally from the US Forest Service, dates from between 1900 and 1930. It forms part of the Frank and Frances Carpenter Collection, which consists of photographs on cultural anthropology and world travel and geography.