The Rise and Fall of the Tallest Mammal to Walk the Earth

It arose from rhino ancestors that were a lot smaller, but Paraceratherium would take a different evolutionary path. Believe it or not, it actually became so big that it probably got close to what scientists think might be the actual upper limit for a land mammal.  The illustration of Paraceratherium used in the thumbnail is by Dmitry Bogdanov!