Edmontosaurus annectens

Edmontosaurus annectens... the biggest hadrosaur in North America. Though on average about 39-40 feet, a fully grown adult (like this one shown here) could reach around 50 feet in length, larger than even the biggest Tyrannosaurus rex, their main enemy. However, such giants were extremely rare due to disease, environmental stresses and predation. However, once the lucky ones did reach such a size, it is quite likely that few if any predators would even dare to attack one.