Because of research and discovery, scientists have recently concluded that because of their unique hip structure, the legs of dinosaurs went straight down below the dinosaur instead of sprawled out to the sides like crocodiles, iguanas, and other reptiles. Dinosaurs are classified into two groups based on their hip structure: Ornithischia (bird-hipped) and Saurischia (lizard-hipped). The differences are evident below:
New discoveries also made paleontologists realize that dinosaurs did not drag their tails along the ground. This position would put them terribly out of balance. Their spine entitles the tail to stick straight out from the back, and it counterbalanes the rest of their body weight. Dinosaurs with larger heads or long necks have longer tails to counterbalance.