This is the theory that species change over time.

He is the English naturalist who developed the theory of evolution by natural selection.

This is a group of closely related organisms that are capable of mating and producing fertile offspring.

This is the place off the coast of South America where Darwin made many of his observations.

This is any characteristic of an organism that improves its chances of survival in its environment.

This is the process by which individuals who are better adapted to their environment are more likely to survive and reproduce.

This is the idea that organisms produce many more offspring than are capable of surviving in an environment.

These are the differences that exist among members of the same species.

This phrase is used by scientists to describe the idea that “only the strong will survive.”

This is the separation of a group of organisms by land forms or other large barriers that can lead to evolution.

This is the fight or struggle between organisms of the same species for survival.

This is the preserved remains or traces of an organism that lived in the past.

This type of fossil is formed when a whole organism is trapped in amber, ice, or tar.

This type of fossil appears as a 3-dimensional replica of an organism.

Fossils are most typically found in this type of rock.

This is the way scientists determine the actual age of a fossil.

Scientists use this law to determine the relative or approximate age of fossils found in rock layers.

Based on the above image, this is the oldest rock layer.

This is the millions of fossils scientists have collected throughout Earth's history.

This is a “calendar” that shows the history of life on Earth over its long history.

This is the approximate age of the Earth.

Dinosaurs evolved and became extinct all during this time period.

Humans are believed to have evolved during this time period.

Species that have similar DNA sequences are believed to have evolved from this past organism.

These are similar structures that show an evolutionary relationship between different organisms.