Animal locomotion for other modes of locomotion. Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. Some pinnipeds perform a similar behaviour called "sledding". Some animals are specialized for moving on non-horizontal surfaces. One common habitat for such climbing animals is in trees, for example the gibbon is specialized for arboreal movement, traveling rapidly by brachiation. Another case is animals like the snow leopard living on steep rock faces such as are found in mountains. Some light animals are able to climb up smooth sheer surfaces or
Lost Animals of the 20th Century such is unavailable, the live materials feature existing species that share the closest characteristics with the extinct animal. Although the show specifically deals with animals that have become extinct, there was one episode that featured the theme of animals which were thought to be extinct, but have been rediscovered. Such has also been the case of some previously featured animals in the show, as scientists have eventually rediscovered extant populations or are attempting to revive species through selective breeding/cloning. Among the animals featured are: Lost Animals of the 20th Century Lost Animals of the 20th Century is a 16-episode documentary