Final answer:
Homologous structures are features that share a common ancestry but not necessarily a similar function. These structures are crucial for understanding an organism's phylogeny as they indicate shared evolutionary paths, unlike analogous structures, which have similar functions but do not indicate a common ancestry.
Step-by-step explanation:
The type of features that share a common ancestry but not necessarily similar functions are called homologous structures. These structures come from a similar embryonic origin and demonstrate a shared evolutionary path. For example, the bones in a whale's front flipper and the bones in the human arm are considered homologous because they originate from a common ancestor despite their different functions today.
In contrast, analogous structures have similar functions but did not arise from a common ancestor, such as the wings of butterflies and birds Understanding whether traits are homologous or analogous is crucial for scientists as it informs them about the phylogeny of the organisms, which is the study of their evolutionary history and relationships.