Size comparison of the holotype specimen of the Upper Jurassic North American diplodocid sauropod Kaatedocus siberi. This specimen is not fully grown. The human silhouette is from File:Silhouette of man standing and facing forward.svg (CC0).
References
Tschopp, Emanuel; Mateus, Octávio (2013). "The skull and neck of a new flagellicaudatan sauropod from the Morrison Formation and its implication for the evolution and ontogeny of diplodocid dinosaurs". Journal of Systematic Palaeontology 11 (7): 853-888.
Barosaurus skeletal diagram by Scott Hartman
Own work
Slate Weasel