This dinosaur restoration is inaccurate, or its accuracy is disputed.
Reason: Pronated hands, likely didn't rear up.
You may ask further questions about the accuracy of this image at the image review page of WikiProject Dinosaurs on the English Wikipedia. Note that this image may be appropriate to illustrate obsolete paleontological views.
Mamenchisaurus sp. adolescent sauropod dinosaur from the Upper Jurassic of China (public display, Field Museum of Natural History, Chicago, Illinois, USA) (cast based on specimens from Xinjiang Province and Sichuan Province).
Sauropod dinosaurs were the largest terrestrial animals ever. They all have the same basic body plan: large body with four walking legs, very long neck & tail, and a small head relative to body size. Sauropods were herbivores, and are often perceived as holding their heads & necks up high to reach vegetation normally out of reach to other organisms. Modern reconstructions of many sauropod species depict them with heads and necks held close to the horizontal, or at low angles above the horizontal.