Mammoth construction of the Great Pyramid of ancient Egypt. The earliest known proboscideans, the clade that contains the elephants, existed about 55 million years ago around the Tethys Sea area. The closest relatives of the Proboscidea are the sirenians and the hyraxes. The family Elephantidae is known to have existed six million years ago in Africa, and includes the living elephants and the mammoths. Among many now extinct clades, the mastodon is only a distant relative of the mammoths, and part of the separate Mammutidae family, which diverged 25 million years before the mammoths evolved. The following cladogram shows the placement
Mastodon (software) and federated timelines. The local timeline shows messages from users on a singular instance, while the federated timeline shows messages across all participating Mastodon instances. Users can communicate across connected Mastodon instances with usernames similar in format to full email addresses. In early 2017, journalists distinguished Mastodon from Twitter for its approach to combating harassment, one of Twitter's largest issues. Mastodon uses community-based moderation, in which each instance can limit, or filter out undesirable types of content. For example, the flagship instance, Mastodon.social, bans content that is illegal in Germany or France, including Nazi symbolism, Holocaust denial and discrimination. Several