Paleontologists at the University of Alberta explained how dinosaurs managed to walk and stand on two feet instead of four. Earlier animals are known as proto-dinosaurs initially walked and stood on four feet. Nevertheless, at some point, they developed to stand upright. This was later passed on to their descendants which drawn up to be even larger.
The theory is that proto-dinosaurs developed to be bipedal to use their forelimbs to catch their prey. Scott Persons, the lead author of the study, argued that this theory is not founded. He argued that this theory still stands for some early dinosaurs which were carnivorous, there are still much other herbivorous which later evolve to be bipedal.
Persons stated that the key to this evolution towards bipedal dinosaurs lies in the muscles at the base of the tail which helped power the hind legs of proto-dinosaurs, determining them to run further and faster. Thus, hind legs developed to become even longer, while front limbs became shorter to improve balance and reduce body weight.
Some proto-dinosaurs gave up on standing and walking on all four legs, learning to stand on two feet. However, later on, some species of dinosaurs went back to walking on four legs. These creatures had heavy plates and horns around their heads which would have helped them balance upright. Over time, herbivores evolved into creatures with bigger guts able to digest cellulose from the plants they fed on.
Persons stated that this indicated that the animal added on weight on their front half, tending to tip the dinosaur down. It was difficult for them to balance on their back legs. In the groups of dinosaurs where speed did not matter, they went back to standing and walking on four legs. Scientists analyzed why the mammals which move fast today, like cheetahs or horses, do not stand upright.
Approximately 250 million years ago, in the Permian period, some animals appeared to start losing the powerful tail muscles. Around that time, many animals became burrowers, needing strong front limbs for digging. Their big tails and back legs would not have helped them maneuver underground, being easier for predators to catch them. Scientists claim that living underground might have helped those creatures survive extinction.
Image source: wikipedia