the preserved remains or traces of living things in the past

The hollow area in a sediment in the shape of an organism

Where a mold was filled with sediment to make a solid copy in the shape of the organism

Where minerals replace all or parts of an organism

an extremely thin coating of carbon on a rock that leaves an impression of the organism behind

provide evidence of the activities of ancient organisms; such as footprints

When all or part of an organism is preserved by tar, sap, or ice

Many differences that exist within a population

Scientists who study fossils

the change in living things over time

If an organism no longer exists and will never live on Earth again

When a group of organisms has few remaining members left living

The age of one object compared to another

The exact age of an object

Each layer is older than the one above it

Igneous rock layer formed when lava flowed on Earth's surface

Lava that pushes up through a rock then cools inside the Earth. Younger than the rock around it.

A break in Earth's crust

Fossils that are widely distributed, living a short period of time to determine the relative age of other rocks and fossils

A gap in the geologic record typically due to erosion

Process in which radioactive elements breakdown releasing energy.

Time it takes for a radioactive element to decay

A record of the geologic events and evolution of life forms found in the fossil record

Larger unit of geologic time which includes the Paleozoic, Mesozoic, and Cenozoic.

Unit of geologic time that eras are divided into

Smallest unit of geologic time; what periods are divided into

Earliest and longest time in Earth's history with mostly single celled organisms.

Time dominated by marine life such as trilobites and brachiopods, first land plants and animals arise.

An animal with a backbone

An animal without a backbone

Time dominated by reptiles and cone-bearing plants, mammals and birds appeared

Time dominated by mammals and flowering plants, marked with a series of ice ages

A group of similar organisms that are able to reproduce fertile offspring

A trait of the body that helps an organisms survive and reproduce

The way an animal acts that helps it survive and reproduce

The process by which organisms best adapted to their environment survive and change the population over time.

Pattern of evolution characterized by the slow and steady accumulation of genes or traits

Differences that exist among members of a population

Structures that are similar in different species and have been inherited by an ancestor

A group of similar organisms that live in a particular area.

A well tested theory for a range of certain observations

The young of two animals that have reproduced