Fossil
Any evidence of once-living organisms such as an imprint or bone
Half-life
Time required for one half of a radioactive isotope to disintegrate
Natural selection
Process that ensures the survival of the fittest in a particular environment
Embryo
Plant or animal in the early stage of development
Gene pool
All of the genes of a given population
Adaptions
Physical and behavioral traits that enable organisms to survive
Homologous
Body parts that are similar in structure and not necessarily similar in function
Analogous structures
Body parts that are similar in function but not similar in structure
Vestigial structures
Body parts that are reduced in size and/ or have no known function
Evolution
Change that occurs in a population during a sequence of generations of organisms over a long period of time structures