The text suggests that the ancestor of modern seals likely had legs with five fingers rather than fins, indicating a land-dwelling origin. This assertion highlights a transition from land to aquatic adaptation, revealing the evolutionary journey of these animals. The notion of leg-like limbs implies a capacity for walking, supporting the idea that seals once thrived in terrestrial environments.

Furthermore, the development of limb bones in various mammals, such as monkeys, horses, and bats, is attributed to evolutionary principles, particularly the concept of utility. As species adapted to their specific environments, bone structures changed, often through reduction and modification, revealing a shared ancestry with fish-like characteristics in their distant past.