Comparative Anatomy MS-LS4-3
NGSS

A biological classification system based on evolution from a shared ancestral line
Cladistics
A biological classification system based on evolution from a shared ancestral line. Cladistics. Cladistics is a way to organize living things by looking at their shared ancestors and evolution patterns, like building a family tree of species.

A similar structure in different species, like a whale fin, bat wing and your arm
Homologous structure
A similar structure in different species, like a whale fin, bat wing, and your arm. Homologous structure. Homologous structures are body parts in different species that have the same basic layout but may serve different functions, showing common ancestry.

A structure that was useful to an ancestor but is no longer functional, like the appendix
Vestigial structure
A structure that was useful to an ancestor but is no longer functional, like the appendix. Vestigial structure. A vestigial structure is a body part that has lost its original use over time because it is no longer needed for survival.