Some dinosaurs could rise up like giants — until they grew too big

Certain smaller sauropods could stand on their hind legs with surprising ease, giving them access to higher food and a defensive edge. Computer simulations show their bones handled stress better than those of their larger relatives. However, as they grew, the sheer weight made this posture much harder to sustain. What started as a useful trick in youth became a more limited, strategic move in adulthood.