Year 6 Science: Fossils show living things long ago
Part of the Year 6 Science fossils and living things over time chapter. Chapter overview · whole chapter on one page
Fossils show living things long ago
Fossils tell us about living things that inhabited the Earth millions of years ago. In an undisturbed cliff, the lower layers are older, because they were laid down first. The age of each layer tells us how long ago the fossil formed.
The cliff below is made up for these questions. Its ages are invented numbers.
The table gives the fossil and the age of each layer.
| Layer | Fossil | Age (million years) |
|---|---|---|
| A | a shell | 10 |
| B | a leaf | 25 |
| C | a fish | 60 |
| D | a footprint | 120 |
| E | a bone | 200 |
Key ideas
- Lower layers in an undisturbed cliff are older.
- Each fossil tells us about a living thing that lived in that layer's time.
- The age of a fossil is the age of the layer where it is found.
- Compare ages by subtracting the smaller number from the larger number.
Method. Find the largest age.
- Read the ages. The largest age is 200 million years, in layer E.200
- Write the name. So the oldest fossil is the bone.a bone
- Write the answer. a bone
Check. The bottom layer is the oldest in this cliff. ✓
Method. Subtract the younger age from the older age.
- Read the ages. Layer D is 120 million years old, and layer B is 25 million years old.120 and 25
- Subtract. The difference is 120 minus 25.120 - 25 = 95
- Write the answer. 95 million years
Check. 25 + 95 = 120. ✓
Method. Add the five ages, then divide by 5.
- Add. The total of the five ages is 10 + 25 + 60 + 120 + 200.415
- Divide. Divide 415 by 5 layers.415 divided by 5 is 83
- Write the answer. 83 million years
Check. 5 times 83 is 415. ✓
Watch out
Watch out: the age of a fossil is the age of its layer, not of the living thing that you can see. Read the table carefully.
Exam tip
Exam tip. When you compare ages, give the unit, which here is millions of years.
Try it (with your teacher, or a grown-up at home). Make a simple cliff from layers of clay or play dough, one colour for each layer, with a small object pressed into one layer. Write the order of the layers, the oldest at the bottom. Explain which layer the object would be found in, if the top layers were worn away.
Exercise 5C Fossils show living things long ago
Method. Find the shell in the table.
- Read the fossils. The shell is in the top layer, layer A.A
- Write the letter. So the letter is A.A
- Write the answer. A
Check. The shell is the youngest fossil in this cliff. ✓
Method. Find layer C.
- Read the row. Layer C holds a fish.fish
- Write the name. So the fossil is a fish.a fish
- Write the answer. a fish
Check. Layer C is aged 60 million years. ✓
Method. Read the table.
- Read the age. Layer C is 60 million years old.60
- Write the number. So the answer is 60.60
- Write the answer. 60
Check. Layer C is between layers B and D in age. ✓
Method. Find the smallest age.
- Read the ages. The smallest age is 10 million years, in layer A.10
- Write the letter. So the youngest layer is A.A
- Write the answer. A
Check. Layer A is at the top of the cliff. ✓
Method. Read the table.
- Read the row. Layer B holds a leaf.leaf
- Write the name. So the fossil is a leaf.a leaf
- Write the answer. a leaf
Check. A leaf is a plant fossil. ✓
Method. Subtract the youngest from the oldest.
- Read the ages. Layer E is 200 million years and layer A is 10 million years.200 and 10
- Subtract. The difference is 200 minus 10.200 - 10 = 190
- Write the answer. 190
Check. 10 + 190 = 200. ✓
Method. Compare the ages.
- Read the ages. Layer C is 60 million years old, and layer B is 25 million years old.60 and 25
- Decide. Since 60 is more than 25, the fish is older, so the answer is yes.yes
- Write the answer. yes
Check. Layer C is lower down in the cliff than layer B. ✓
Method. Look at the different fossils.
- Look at the fossils. The fossils in the layers are different from each other, for example a shell and a bone.different
- Decide. Different fossils in different layers show that living things changed over time.yes
- Write the answer. yes
Check. The fossils come from different times. ✓
Method. Read the age of layer D.
- Read the table. Layer D is 120 million years old.120
- Write the number. So the footprint was made about 120 million years ago.120
- Write the answer. 120
Check. The layer age is the age of the footprint. ✓
Method. Subtract the younger age from the older age.
- Read the ages. Layer D is 120 and layer B is 25.120 and 25
- Subtract. The difference is 120 minus 25.120 - 25 = 95
- Write the answer. 95
Check. 25 + 95 = 120. ✓
Method. Add the five ages, then divide by 5.
- Add. The total of the five ages is 415 million years.415
- Divide. Divide 415 by 5.415 divided by 5 is 83
- Write the answer. 83
Check. 5 times 83 is 415. ✓
Method. Compare the two ages.
- Read the ages. The shell is in layer A, aged 10 million years, and the bone is aged 200 million years.10 and 200
- Decide. So the shell is younger, and the answer is yes.yes
- Write the answer. yes
Check. The shell is at the top, and the bone is at the bottom. ✓
Method. Think about how layers form.
- Think about the order. Layers build up one on top of another over time.on top
- Think about the bottom. So the layer at the bottom was laid down first, and is the oldest.first
- Write the answer. Accept any sentence that says layers build up over time, so the layers laid down first are at the bottom and are the oldest.
Check. This only holds if the cliff has not been turned over. ✓
Method. Compare the fossils.
- Compare the fossils. A shell and a bone come from different kinds of living thing.different
- Compare the times. They lived 190 million years apart, so they lived at different times.different times
- Write the answer. Accept any sentence that says a shell and a bone come from different living things that lived at very different times.
Check. The ages show the time gap. ✓
Method. Think about a fossil.
- Think about the fossil. A fossil is the preserved remains of a living thing.remains
- Think about the time. The shell is 10 million years old, so it is not alive today.not alive
- Write the answer. Accept any sentence that says the shell is a preserved remain from 10 million years ago, not a living animal today.
Check. The age of the layer tells us when it lived. ✓