Earth Science: Fossils Evidence of Ancient Life
Using fossils to learn about organisms and environments from long ago
Earth Science: Fossils Evidence of Ancient Life
Using fossils to learn about organisms and environments from long ago
Earth Science - Grade 4-5
- 1
What is a fossil? Write a definition in your own words.
Think about clues from plants or animals that lived in the past.
A fossil is the preserved remains, traces, or impressions of an organism that lived long ago. Fossils can include bones, shells, footprints, leaves, or shapes left in rock. - 2
A scientist finds a shell fossil in a layer of rock far from the ocean. What might this fossil be evidence of?
The shell fossil could be evidence that the area was once covered by an ocean, sea, or other body of water. It shows that the environment in that place may have changed over time. - 3
Put these events in the correct order for how a body fossil can form: sediment hardens into rock, an animal dies, the animal is buried by sediment, minerals replace parts of the animal.
Start with the living thing and end with rock.
The correct order is: an animal dies, the animal is buried by sediment, minerals replace parts of the animal, and sediment hardens into rock. This process can preserve the animal as a fossil. - 4
Explain the difference between a body fossil and a trace fossil.
A body fossil is part of an organism, such as a bone, tooth, shell, or leaf. A trace fossil is evidence of an organism's activity, such as a footprint, burrow, nest, or bite mark. - 5
Look at a fossil footprint. What can a footprint fossil tell scientists about an ancient animal?
Think about what your own footprints can show in mud or sand.
A footprint fossil can tell scientists about the animal's size, how it moved, how many legs it may have had, and the type of surface it walked on. A trail of footprints can also show the direction it traveled. - 6
Why are fossils usually found in sedimentary rock instead of igneous rock?
Fossils are usually found in sedimentary rock because sediment can gently bury dead organisms and preserve them. Igneous rock forms from hot melted rock, which would usually destroy remains of plants and animals. - 7
A fossil leaf has the same shape as leaves from plants that live in warm, wet places today. What might scientists infer about the ancient environment?
Compare the fossil plant to plants that live in modern environments.
Scientists might infer that the ancient environment was warm and wet when the fossil leaf formed. Fossils can give clues about the climate and habitats of the past. - 8
Why is finding a complete dinosaur skeleton very rare?
Finding a complete dinosaur skeleton is rare because many things can happen after an animal dies. Bones may be scattered, eaten, broken, weathered away, or not buried quickly enough to become fossils. - 9
A rock layer contains fish fossils. A higher rock layer contains land plant fossils. What does this suggest about how the environment may have changed?
In undisturbed rock layers, lower layers are usually older than higher layers.
This suggests that the area may have changed from a water environment to a land environment over time. The lower fish fossils show older watery conditions, and the higher plant fossils show later land conditions. - 10
How do fossils help scientists learn about animals that are extinct?
Fossils help scientists learn about extinct animals by showing their body parts, shapes, sizes, teeth, and sometimes footprints or nests. These clues help scientists understand how the animals lived. - 11
A student says, 'Fossils are just old rocks, so they do not give evidence about living things.' Explain why the student is incorrect.
Use the words remains, traces, and evidence in your answer.
The student is incorrect because fossils are remains or traces of living things preserved in rock. They give evidence about plants, animals, and other organisms that lived long ago. - 12
Name two examples of trace fossils and explain what each one shows.
A footprint is a trace fossil that shows where an animal walked and how it moved. A burrow is a trace fossil that shows where an animal dug or lived. - 13
A fossil of a sea creature is found in a mountain. What is one possible explanation for how it got there?
Remember that land can be lifted, folded, or changed by Earth processes over long periods of time.
One possible explanation is that the rock in the mountain formed from sediments that were once under an ancient sea. Over a very long time, Earth movements lifted the rock upward to form mountains. - 14
Why do scientists compare fossils with living organisms?
Scientists compare fossils with living organisms to understand what ancient organisms may have looked like, what they ate, and where they lived. Similar body parts can help scientists make careful inferences. - 15
Create a claim using fossil evidence: A rock contains many fossilized fern leaves and no desert animal fossils. What can you claim about the ancient environment, and what evidence supports your claim?
A claim tells what you think, and evidence tells what clues support it.
A reasonable claim is that the ancient environment was likely moist enough for ferns to grow. The evidence is that many fern leaf fossils were found, and ferns usually grow in damp environments rather than dry deserts.