Mammals

They are very fast. Their cleat-like/non-retracting claws prevent slipping. They have much larger psoas muscles compared to greyhounds for a huge hip extension force while running. Their long/stiff tail helps them balance.

Kangaroos in Australia are very energy-efficient runner. They often spend less energy for faster speed. They are not found in other areas. The heavy tail helps extend hip joints during hopping through lever action achieved by psoas muscles and caudofemoralis muscles. For faster speeds, they keep more upright postures. However, the tail will drag/push them [...]