Final answer:
The evolution of the earliest tetrapods included the development of feet with digits, which was crucial for terrestrial locomotion. This change was part of a broader trend in their skeleton adapting for land life.
Step-by-step explanation:
A trend in the evolution of the earliest tetrapods was the appearance of feet with digits. These early tetrapods, such as Ichthyostega and Acanthostega, had limbs with a skeletal structure similar to that found in present-day tetrapods including feet with digits which is a significant adaptation for living on land.