8.1 Science

What are fossils?

Fossils are the remains or evidence of once-living organisms.

How do fossils help us?

Fossils help us understand how organisms have changed over time.

What parts of organisms typically fossilize?

Only hard parts such as bones, shells, and teeth typically fossilize.

What is mineralization?

Mineralization is a process where minerals fill in small spaces and replace tissues to form fossils.

What is carbonization?

Carbonization occurs when pressure drives out an organism's liquids and gases, leaving only the carbon outline.

How are molds and casts formed?

Molds and casts are fossils formed when sediments encase hard parts of an organism.

What is original material in fossils?

Original material refers to cells that are buried in a deoxygenated environment where bacteria cannot break them down.

What does the fossil record show?

The fossil record shows all the fossils that exist and demonstrates change over time.

What is relative-age dating?

Relative-age dating uses the layers of rock to determine the relative ages of fossils.

What is absolute-age dating?

Absolute-age dating uses the decay of carbon to assign a specific age to carbonized fossils.

What is the geologic time scale?

The geologic time scale is a chart that divides Earth's history into different time units.

What are the largest divisions of the geologic time scale?

The largest divisions are eons and eras.

What are epochs?

Epochs are the smallest divisions of geological time, reflecting changes in climate, geology, or life.

What caused mass extinction events?

Mass extinction events are typically caused by environmental changes.

What can sudden changes cause in the fossil record?

Sudden changes like tectonic plate movement and sea level changes can cause extinction events.

How do fossils change over time?

Fossils show common ancestors of modern organisms that shared similar body plans and structures.