LIFE SCIENCE

Detailed explanation-1: -But beneath the skin, the forelimb bones of these animals are startlingly similar. These likenesses in structure, called homologies, are the result of descent from a common ancestor.

Detailed explanation-2: -Anatomy and Embryology For example, the bones in the appendages of a human, dog, bird, and whale all share the same overall construction (Figure 2) resulting from their origin in the appendages of a common ancestor.

Detailed explanation-3: -We use homologous characters-characters in different organisms that are similar because they were inherited from a common ancestor that also had that character. An example of homologous characters is the four limbs of tetrapods. Birds, bats, mice, and crocodiles all have four limbs. Sharks and bony fish do not.

Detailed explanation-4: -Homologous structures are anatomical structures in organisms that share the same basic form. For example, the bones in the appendages of humans, dogs, birds, and whales all share the same overall construction resulting from their origin in the appendages of a common ancestor.