Shaping the Earth: Landscapes and Change · Term 3

Fossils and Earth's History

Using fossil evidence to reconstruct past environments and understand how life on Earth has changed over millions of years.

About This Topic

Fossils provide a window into the ancient past, allowing students to reconstruct ecosystems that existed millions of years ago. In the Ontario curriculum, this topic helps students understand that the Earth is constantly changing and that life has evolved in response to those changes. Students will learn how fossils form and what they can tell us about the climate and geography of prehistoric Canada, such as the fact that much of Ontario was once covered by a warm, shallow sea.

This unit also touches on the work of paleontologists and the importance of protecting fossil sites. It is a great opportunity to discuss the Burgess Shale in British Columbia as a world-renowned Canadian fossil site. This topic comes alive when students can physically model the patterns of fossilization through hands-on 'excavations' and collaborative reconstructions.

Learning Objectives

• Classify different types of fossils based on their formation process.
• Explain how fossil evidence indicates past environmental conditions, such as climate and habitat.
• Analyze the relationship between the type of organism and its likelihood of becoming fossilized.
• Infer past continental positions based on the geographic distribution of specific fossils.
• Construct a timeline illustrating major changes in life forms on Earth as evidenced by the fossil record.

Before You Start

Characteristics of Living Things

Why: Students need to understand what defines a living organism to recognize fossilized remains as evidence of past life.

Earth's Materials and Resources

Why: Understanding different types of rocks and how they form provides context for how fossils are preserved within rock layers.

Key Vocabulary

fossil	The preserved remains or traces of ancient organisms, providing evidence of past life.
paleontology	The scientific study of fossils and ancient life, conducted by paleontologists.
fossilization	The process by which organic matter is replaced by minerals, preserving the shape and structure of an organism.
trace fossil	Evidence of an organism's activity, such as footprints, burrows, or coprolites (fossilized feces), rather than the organism itself.
index fossil	A fossil of an organism that lived for a short period but was widespread, used to date rock layers.

Active Learning Ideas

Inquiry Circle: Making Trace Fossils

Students use clay and various objects (shells, leaves, plastic dinosaurs) to create 'molds' and 'casts.' They swap their molds with another group who must try to identify the 'organism' and what it was doing based on the print.

⏱ 45 min·Small Groups

Generate mission

Simulation Game: Layers of Time

Using different colors of sand or soil in a clear container, students 'bury' objects at different levels. They then 'excavate' them and discuss why the objects at the bottom are usually the oldest, simulating the law of superposition.

⏱ 40 min·Small Groups

Generate mission

Think-Pair-Share: The Mystery Fossil

Show a picture of a strange fossil (like an Anomalocaris). Pairs must brainstorm three things they can tell about its environment (e.g., did it live in water or on land?) based only on its physical features.

⏱ 20 min·Pairs

Generate mission

Real-World Connections

Paleontologists at the Royal Tyrrell Museum in Drumheller, Alberta, study dinosaur fossils to understand prehistoric ecosystems and the evolution of life in Canada.

Geologists use fossil evidence, like the distribution of ancient marine life fossils found in landlocked areas of Ontario, to reconstruct the movement of tectonic plates and the history of continental drift.

Museum exhibits, such as those at the Canadian Museum of Nature in Ottawa, showcase fossils to educate the public about Earth's long history and the changes in life over millions of years.

Watch Out for These Misconceptions

Common Misconception

Fossils are actually pieces of bone or wood.

What to Teach Instead

Fossils are usually rock; the original organic material has been replaced by minerals. Having students handle a real fossil versus a modern bone helps them feel the difference in weight and texture.

Common Misconception

All living things eventually become fossils.

What to Teach Instead

Fossilization is extremely rare and requires very specific conditions (like quick burial). A 'fossilization game' where students see how many 'organisms' are eaten or rot away before they can be buried helps illustrate this.

Assessment Ideas

Quick Check

Provide students with images of different fossils (e.g., ammonite, trilobite, dinosaur footprint, leaf imprint). Ask them to identify each fossil and write one sentence explaining what it tells us about the past environment.

Discussion Prompt

Pose the question: 'Why are shells and bones more likely to become fossils than soft tissues like leaves or jellyfish?' Facilitate a class discussion where students use their understanding of fossilization to explain the differences.

Exit Ticket

Give each student a card with a fossil location (e.g., 'Fossils of tropical plants found in northern Canada'). Ask them to write two sentences inferring what this fossil location suggests about Earth's past climate and continental position.

Frequently Asked Questions

How can active learning help students understand fossils?

Since we can't visit the past, active learning through simulations and modeling is essential. When students create their own 'fossils' using clay and plaster, they understand the physical process of mold and cast formation. 'Excavating' a cookie or a sand tray helps them appreciate the patience and precision required in real paleontology.

Where can you find fossils in Ontario?

The Niagara Escarpment and the shores of the Great Lakes are excellent places to find fossils of ancient sea creatures like trilobites and brachiopods.

What is the difference between a body fossil and a trace fossil?

A body fossil is a part of the actual organism (like a tooth), while a trace fossil is a sign that the organism was there (like a footprint or a burrow).

How do fossils prove that Canada's climate has changed?

We find fossils of tropical plants and coral reefs in parts of Canada that are now very cold, proving that the land was once in a much warmer climate zone.