Question

1. trilobites and ammonites are some of the oldest fossils found in these rock layers.
2. trilobites went extinct before ammonites.
3. fossil evidence indicates mammals evolved around the same time that dinosaurs went extinct.
4. fossil evidence of shelled organisms indicates they evolved before plants and dinosaurs.

which option provides the most likely natural position of the rock layers, from deepest to most shallow, based on the law of superposition?
a. n, o, m, p, q
b. q, p, m, n, o
c. o, p, q, m, n
d. n, m, p, o, q

Explanation:

Step1: Recall the law of superposition

The law of superposition states that in undisturbed rock layers, the oldest layers are at the bottom (deepest) and the youngest are at the top (shallowest). So we need to order the layers from oldest (deepest) to youngest (shallowest) based on the fossil evidence.

Step2: Analyze the fossil evidence

• From statement 1: Trilobites and ammonites are old.
• Statement 2: Trilobites went extinct before ammonites, so trilobites are older than ammonites.
• Statement 3: Mammals evolved around dinosaur extinction, so mammals are younger than dinosaurs (since dinosaurs went extinct, and mammals evolved then).
• Statement 4: Shelled organisms (like trilobites/ammonites) evolved before plants and dinosaurs.

So the order of evolution (oldest to youngest) should be: shelled organisms (trilobites, ammonites) → plants/dinosaurs → mammals.

Now let's match to the options:

• Option A: N,O,M,P,Q. Let's assume N (shelled), O (shelled/ammonite), M (dinosaur/plant), P (mammal?), Q (mammal?). Wait, maybe better to see the layer order. Wait, the key is the oldest at the bottom (deepest). So the deepest layer has the oldest fossils.

From the fossil info:

1. Trilobites (oldest) and ammonites (older than mammals/dinosaurs? Wait no: statement 2: trilobites extinct before ammonites, so trilobites are older than ammonites. Statement 4: shelled (trilobites, ammonites) evolved before plants and dinosaurs. Statement 3: mammals evolved after dinosaurs (since dinosaurs went extinct, and mammals evolved then). So the order of fossils from oldest to youngest:

Trilobites (oldest) → ammonites (next) → plants/dinosaurs → mammals.

Now let's look at the options:

Option A: N,O,M,P,Q. Let's say N is trilobites, O is ammonites, M is dinosaurs/plants, P is mammals, Q is later mammals? Wait, maybe the layers are ordered from deepest (oldest) to shallowest (youngest) as N (oldest, trilobites), O (ammonites), M (dinosaurs/plants), P (mammals), Q (youngest). Let's check the other options:

Option B: Q,P,M,N,O. That would be youngest at bottom, which is wrong.

Option C: O,P,Q,M,N. Also wrong order.

Option D: N,M,P,O,Q. No, M after N? Maybe not.

Wait, the law of superposition: deepest (oldest) to shallowest (youngest). So the correct order should have the oldest fossils at the bottom. From the fossil evidence, the oldest are trilobites/ammonites (shelled), then plants/dinosaurs, then mammals. So the order from deepest (oldest) to shallowest (youngest) should be the oldest fossils first. So option A: N,O,M,P,Q. Let's confirm:

• N: oldest (trilobites)
• O: next (ammonites, since trilobites extinct before ammonites, so ammonites are younger than trilobites but older than dinosaurs/plants)
• M: next (dinosaurs/plants)
• P: next (mammals, since mammals evolved after dinosaurs)
• Q: youngest (maybe later mammals)

So option A is the most likely as it orders from oldest (deepest) to youngest (shallowest) based on the fossil evidence and superposition.

Answer:

A. N,O,M,P,Q