The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth's Past Mass Extinctions

by Peter Brannen

Spores of a fungus that lived and relied on mastodon dung hint that this extinction wasn’t due to natural forces like a shift in vegetation or climate change. The spores plummeted—indicating the disappearance of the mastodons and other megafauna they depended on—even as the animals’ preferred spruce forests were spreading. Native American kill sites, as well as computer models simulating the relative ease of overhunting the megafauna to extinction in only a few generations, point to another culprit. North America also lost its many camels, which originated and evolved on the continent, only later spreading out into Asia and Africa. When camels were experimentally employed in military convoys across the Southwest in the 1850s, Lieutenant Edward Beale—unaware of the animals’ ancestral connection to the land—was pleasantly surprised by their uncommon effectiveness. Happily marching across their evolutionary homeland, they ate “the otherwise worthless weeds and other plants shunned by livestock, including creosote bush growing along the right of way in New Mexico.”