What adaptation allows running mammals to achieve speed?

The adaptation that allows running mammals to achieve speed is primarily attributed to elongated leg bones. This adaptation provides several biomechanical advantages, including a greater stride length and the ability to cover more ground with each step. Longer leg bones contribute to increased leverage and allow for more powerful muscle contractions, which enhance overall speed.

While adaptations such as a very large scapula and the loss of toes can play roles in locomotion, they do not directly contribute to speed as effectively as elongated leg bones do. The scapula, while important for the attachment of muscles, does not influence the length of the strides as directly. Similarly, the loss of toes may help to streamline the foot and reduce weight, but it’s the lengthening of the bones that fundamentally allows for quicker movement.

Therefore, focusing on elongated leg bones highlights the crucial structural adaptations that enable mammals to run faster and more efficiently.