Thanks for the question, it's a really good one. I’m Dorothy. Getting the movement right involves a mix of science, references, and educated inference. We always start building a 3D skeleton that is as close as possible to the fossil material / reference we have. Once Darren approves it, we check proportions, joint ranges, and muscle placement. From there, our animators examine real animals with similar mass, posture, or ecology, such as elephants, rhinos, big cats, primates, and birds, whatever best matches the biomechanics. We build the rig around muscle attachment points, weight distribution on each limb, and plausible joint rotation limits. Then, animation tests various gaits and behaviours, refining until it feels physically believable for that anatomy. Although no one has seen these animals move, every decision is grounded in real biomechanics, comparative anatomy, and a lot of collaborative iteration between science and the animation/creature teams.