The last of the megaherbivore species, elephants will be the end of a 60-million-year-old lineage of keystone species. A keystone species is one of its kind that has a large impact on the environment, and is indispensable to maintaining the biodiversity of any given ecosystem. The disappearance of such a species from a particular area would be detrimental to that ecosystem. At one point, homo sapiens shared the planet with 42 other species of megafauna or megaherbivores weighing over a ton; now only two such species remain – the African and the Asian elephants