Chapter 3: Geologic Time - The Story of Earth: An Observational Guide - Free Printable

The image presents a puzzle involving fossilized marine organisms: Ammonite, Gastropod, Bivalve, and Trilobite. On the left side, there are six boxes with various combinations of these fossils. On the right side, there are five boxes with different arrangements of the same fossils.

Our goal is to determine which box on the right matches the sequence or pattern of fossils in the left column — possibly indicating that one of the right-side boxes is missing or out of order compared to the left.

Let’s analyze both sides step by step.

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Step 1: Identify the Fossils

From the legend:
- Ammonite: Spiral shell (like a nautilus)
- Gastropod: Small, conical spiral shell (snail-like)
- Bivalve: Clam-like, two-part shell
- Trilobite: Segmented, oval-shaped with three lobes

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Step 2: Analyze Left Column (6 Boxes)

We'll go row by row:

1. Box 1: Ammonite only
2. Box 2: Ammonite + Gastropod
3. Box 3: Trilobite + Gastropod
4. Box 4: Trilobite + Bivalve + Gastropod
5. Box 5: Trilobite + Bivalve
6. Box 6: Trilobite only

So the sequence of fossils from top to bottom is:
- Ammonite → Ammonite+Gastropod → Trilobite+Gastropod → Trilobite+Bivalve+Gastropod → Trilobite+Bivalve → Trilobite

This appears to be a progressive disappearance of certain fossils:
- Ammonite starts and then disappears.
- Gastropod appears in box 2, stays until box 4, then disappears.
- Bivalve appears in box 4, stays in box 5, then disappears.
- Trilobite appears in box 3 and remains until the end.

So the pattern is:
- Ammonite: present in boxes 1–2
- Gastropod: present in boxes 2–4
- Bivalve: present in boxes 4–5
- Trilobite: present in boxes 3–6

It looks like a successive layering and removal of fossils, perhaps representing geological time layers (younger at the bottom).

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Step 3: Analyze Right Column (5 Boxes)

Now check the right column:

1. Box 1: Ammonite only ✔ (matches left box 1)
2. Box 2: Trilobite + Gastropod + Ammonite ✘ (left box 2 has Ammonite + Gastropod, but no Trilobite)
- This is different from left box 2
3. Box 3: Trilobite + Bivalve + Gastropod ✔ (matches left box 4)
4. Box 4: Trilobite + Bivalve ✔ (matches left box 5)
5. Box 5: Trilobite + Bivalve ✘ (left box 6 has only Trilobite, not Bivalve)

Wait — this doesn't match.

Let’s compare each right box to the left:

| Right Box | Fossils Present | Matches Left Box? |
|----------|------------------|-------------------|
| 1 | Ammonite | Yes → Left Box 1 |
| 2 | Trilobite, Gastropod, Ammonite | No → Left Box 2 has only Ammonite + Gastropod, no Trilobite |
| 3 | Trilobite, Bivalve, Gastropod | Yes → Left Box 4 |
| 4 | Trilobite, Bivalve | Yes → Left Box 5 |
| 5 | Trilobite, Bivalve | No → Left Box 6 has only Trilobite |

So only boxes 1, 3, and 4 match exactly.

But notice: The right column has only 5 boxes, while the left has 6.

Also, the order seems off.

Let’s try to reconstruct what should be in the right column if it's supposed to mirror the left.

Left sequence:
1. Ammonite
2. Ammonite + Gastropod
3. Trilobite + Gastropod
4. Trilobite + Bivalve + Gastropod
5. Trilobite + Bivalve
6. Trilobite

So it's a chronological progression of fossil appearances and disappearances.

Now look at the right column again:

1. Ammonite → matches left 1
2. Trilobite + Gastropod + Ammonite → this combines elements from left 2 and 3, but adds Trilobite too early
3. Trilobite + Bivalve + Gastropod → matches left 4
4. Trilobite + Bivalve → matches left 5
5. Trilobite + Bivalve → duplicate of box 4? And doesn’t match left 6

Wait — box 5 on the right has Trilobite + Bivalve, but left box 6 has only Trilobite.

So the last box on the right is incorrect — it should have only Trilobite.

Also, box 2 on the right has Trilobite appearing earlier than it should.

So the right column does not match the left in sequence.

But maybe the puzzle is asking: Which box on the right is missing or misplaced?

Alternatively, perhaps the task is to identify which box on the right corresponds to the missing box in the left, but the left has more boxes.

Wait — actually, the left has 6 boxes, the right has 5, so maybe the right is supposed to be a rearrangement or subset?

Another idea: Maybe the right column is supposed to be a correct stratigraphic sequence, and we need to find which box is out of place.

But let’s consider a common type of puzzle: identify the mismatched box.

Looking closely:

- Right box 2 has Ammonite + Trilobite + Gastropod
- But in reality, Ammonites and Trilobites did not live at the same time.

That’s a key point!

Paleontological Fact Check:

- Trilobites: Extinct since the end of the Permian period (~250 million years ago)
- Ammonites: Appeared later, in the Devonian, and went extinct at the end of the Cretaceous (~66 million years ago)
- So Trilobites and Ammonites did not coexist — they are separated by about 100 million years.

Therefore, any box showing both Trilobite and Ammonite together is geologically impossible.

In the left column:
- Box 1: Ammonite only → OK
- Box 2: Ammonite + Gastropod → OK (both lived in Mesozoic)
- Box 3: Trilobite + Gastropod → Possible? No — most gastropods didn’t appear until after trilobites died out.

Wait — gastropods existed long before ammonites, and even before trilobites? Actually, gastropods first appeared in the Cambrian, same as trilobites.

So Trilobite + Gastropod is plausible.

But Trilobite + Ammonite is not possible — they are from different eras.

So in the right column, box 2 shows:
- Trilobite + Gastropod + Ammonite → Impossible! Because Trilobite and Ammonite did not coexist.

Whereas in the left column, no box has both Trilobite and Ammonite — good.

So the error is in the right column, box 2.

Moreover, right box 5 has Trilobite + Bivalve, but left box 6 has only Trilobite — so that might be a mistake too.

But the biggest error is the coexistence of Trilobite and Ammonite.

Conclusion:

The problem is likely to identify the box that contains an impossible combination based on geological time.

Thus, the correct answer is: the second box on the right (top to bottom), because it contains Ammonite and Trilobite together, which is geologically impossible.

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Final Answer:

✔ The second box on the right is incorrect because it shows Ammonite and Trilobite together, but these organisms did not live at the same time in Earth's history.

This violates the principle of faunal succession in geology.

Therefore, the solution is to identify the second box on the right as the one with the error.