How could a single ornithopod be both bipedal and quadrupedal?
a) Certain ornithopods could shift between bipedal and quadrupedal locomotion to facilitate different activities, such as feeding or escaping predators.
b) Ornithopods were exclusively quadrupedal, with no capacity for bipedal locomotion due to their heavy body structure.
c) Certain ornithopods had specialized joints that allowed them to switch between bipedal and quadrupedal stances depending on their speed and terrain.
d) Ornithopods primarily relied on quadrupedal locomotion, and any bipedal movement was minimal and not a significant part of their behavior.
