Question

name any two homologous structures in vertebrates . why are they called so ?
how do such organs help in understanding an evolutionary relationship?

Answer 1

A homologous structure is an example of an organ or bone that appears in different animals, underlining anatomical commonalities demonstrating descent from a common ancestor. In other words, it’s when very different animals have bones that appear very similar in form or function and seem to be related.
The tailbone in human beings is so-named because it is a homologous structure to the beginning of many animals’ tails, such as monkeys. It is known as "vestigial" because it is the last vestige of what was once a tail.
All mollusks have a "foot" that they use to travel. This foot is homologous although it may not appear to be immediately – close inspection demonstrates that in terms of form and function, gastropods, cephalopods, and bivalves share this homologous structure in common.
Mammals share the homologous structure of the vertebrae in common. For instance, in spite of its height, the giraffe has the very same number of neck bones (seven) as a giant whale and a tiny human being