Size comparison of the Russian hadrosaurid ornithopod dinosaur Olorotitan arharensis. The human silhouette is from File:Silhouette of man standing and facing forward.svg (CC0). 
References
Godefroit, Pascal; Bolotsky, Yuri L.; Bolotsky, Ivan Y. (2012). "Osteology and relationships of Olorotitan arharensis, a hollow−crested hadrosaurid dinosaur from the latest Cretaceous of Far Eastern Russia". Acta Palaeontologica Polonica 57 (3): 527–560.
Own work
User:Slate Weasel