The word dinosaur was coined by Richard Owen in 1841, deinos (terrible) + sauros (lizard) which describe various extinct reptiles of the orders Saurischia and Ornithischia that flourished during the Mesozoic Era. Dinosaurs were carnivorous or herbivorous, dwelled mostly on land, and varied from the size of a small dog to the largest land animals that ever lived. Trachodon (meaning "rough tooth") was a large duck-billed dinosaur of the Cretaceous period. As a hadrosaurid, Trachodon would have been a large, bipedal/quadrupedal herbivore.