unit 10 lesson 1 what are fossils? - wordpress.com · 10/03/2018 · unit 10 lesson 1 what are...

Unit 10 Lesson 1 What Are Fossils?

Copyright © Houghton Mifflin Harcourt Publishing Company


Traces of the Past


• The preserved remains or traces of a living thing is called a fossil.

• Fossils can be made of: 1. an organism’s hard

parts, such as bones, teeth, and shells,

2. soft parts, which are tissues such as skin and organs. They are rare as bacteria break down soft tissue.

10.1 videos/WHAT'S A FOSSIL - YouTube.mp4

10.1 videos/WHAT'S A FOSSIL - YouTube.mp4


Traces of the Past


• All living things contain the element carbon. Some plant tissues get preserved as carbon films in rock.

• Footprints are examples of trace fossils. These show that an animal was there, even though none of its parts were preserved.

• Scientists study many types of fossils to help them learn about ancient life on Earth.


Traces of the Past


• Most fossils are found in sedimentary rock and can be formed in different ways.

1. Dead animals at the bottom of a body of water can form fossils. Sediment buries the animal, then soft parts decay and hard parts become fossils.


Traces of the Past


2. Minerals, like quartz, can also form fossils by replacing the shell or plant material that made up the organism. This is how petrifiedwood forms.


Traces of the Past


3. Mold and cast fossils are made when an organism, such as a leaf, is pressed into soft mud, leaving a hollow space called a mold.

• A cast forms if the mold is later filled with mud that hardens.


Traces of the Past



Fossils That Burn


• Coal forms from dead plants that end up at the bottom of a lake or pond. Sediment buries the plants.

• Over years, heavy layers of sediment cause the temperature and pressure underground to rise, changing plant material to coal.

• A fossil fuel is an energy-rich resource formed from the buried remains of these once-living organisms.

10.1 videos/Oil and Gas Formation - YouTube.mp4

10.1 videos/Oil and Gas Formation - YouTube.mp4


Fossils That Burn


• Oil and natural gas take millions of years to form from tiny, dead sea organisms at the bottom of the ocean, where they are buried by sediment.

• The weight of sediment and water cause temperature and pressure to rise. Hydrogen and carbon are left, forming oil and natural gas.

• The oil and natural gas are pumped from the ground.


Fossils That Burn


10.1 videos/fossil fuels - YouTube.mp4

10.1 videos/fossil fuels - YouTube.mp4


Fossils That Burn



What Fossils Tell Us


• Scientists who study fossils to learn what life on Earth was like long ago are called paleontologists.

• Fossils show that some types of plants and animals have changed a lot, while others have hardly changed at all.

10.1 videos/paleontologists.wmv

10.1 videos/paleontologists.wmv




• For example, the gingko tree, which has been around for at least 420 million years, has not changed much.

• Organisms that look as if they have not changed much over time can be called living fossils.




• Fish have changed a lot over time. The first fish had no jaws. Later fish developed jaws and heavy armor plates. Today, fish have jaws but no armor.

unit 10 lesson 1 what are fossils? - wordpress.com · 10/03/2018 · unit 10 lesson 1 what are...

Documents