A series of layers of rock in the ground.

The state or process of a species, family, or larger group no longer exists.

The formation of a new, or two new, species.

The process of change by which an organism or species becomes better suited to its environment.

The diversification of a group of organisms into forms filling different ecological niches.

The intentional breeding of plants or animals to produce specific traits.

The process that results in the adaptation of an organism to its environment.

Competition between different species of the same ecological area.

Members of the same species compete for limited resources.

The process by which organisms change over time as a result of changes in heritable physical or behavioral traits.

Mating rituals prevent reproduction between different species.

Members of two different species are unable to reproduce because their ‘parts don’t fit’.

The gametes of two different species are incompatible, and therefore do not produce offspring.

The total of different genes in a population.

An environmental factor that affects an organism's access to resources.

An unborn offspring of an organism.

The geographical distribution of plants and animals.

A population of organisms that are separated from reproducing with other organisms of the same species by geographic features.

A group of organisms that are able produce viable offsprings.

Something that prevents the fertilization of an egg cell.

Something that prevents the survival of an offspring.

When two species occupy separate habitats and therefore cannot reproduce.

When two species mate at different times and therefore cannot reproduce.

The process of comparing anatomical structures to show evolutionary relationships.

An organ or bone that appears in different animals, demonstrating descent from a common ancestor

A structure in an organism that no longer serves a useful function.

The idea that species evolve from shared ancestors.

The hunting and eating of one species by another species.

A species that is hunted by another species.

A geologic doctrine that changes in the earth's crust have in the past been brought about suddenly by physical forces operating in ways that cannot be observed today.

Geological forces at work today are the same as those in the past

A scientist who specializes in the study of life forms that existed in previous geologic periods.

History of life as documented by fossils.

No longer in existence.

A fossil that is useful for dating and correlating the strata in which it is found.

The time required for any specified property to decrease by half.

The geologic time scale is a system of chronological dating that classifies geological strata in time.

A very long span of geologic time.

The basic unit of the geologic time scale.

Spherical structures to be formed when a heated mixture of amino acid molecules in the dry conditions is dissolved in water.

A fossil or fossil fragment that can be seen only with a microscope.

The unified and widely accepted theory of how organelles arose in organisms, differing prokaryotic organisms from eukaryotic organisms.

A large number of species within a relatively short period of geological time.