"The herbivore Ectoconus (a member of the Periptychidae, which may be related to living hoofed mammals, the ungulates) reached about 100kg (220lb) within a few

"The herbivore Ectoconus (a member of the Periptychidae, which may be related to living hoofed mammals, the ungulates) reached about 100kg (220lb) within a few hundred thousand years of the extinction. In geological time, that's the blink of an eye." It's interesting how fast evolution can move when there are open niches.