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
The Sixth Extinction: An Unnatural History naturally found in Panama. This left a puzzling question: how did the fungus get to Panama? Evidence indicates that humans were instrumental in how the fungus traveled. Kolbert uses the frog-fungus relationship as a symbol of how humans are introducing invasive species to various environments, where native species would normally have the proper distribution of alleles for their environment. Kolbert explains how fossils of the American mastodon ("Mammut americanum") shaped Georges Cuvier's views on catastrophism. According to Cuvier, there was no reason the mastodon should have died out. The mastodon was large enough to avoid predation, had large enough teeth