Answer: It's known as the continental drift :)
Explanation: "Pangea's existence was first proposed in 1912 by German meteorologist Alfred Wegener as a part of his theory of continental drift. Its name is derived from the Greek pangaia, meaning “all the Earth.”" (copied from google)
1. The hind limbs tend to be sturdier and stronger
2. Hind limbs are more firmly attached to the spine