Question

The diagram models a cross-section of rock from a certain region.



The life form represented by the fossil in rock layer 1 is not present in any of the layers above it. What is the most likely explanation for this?
A.
The life form evolved into all of the species in the next layer.
B.
The life form became extinct in the region long ago.
C.
The life form only recently evolved.
D.
The life form only recently moved to the region.

Answer 1

B. The life form became extinct in the region long ago.

Reason: Rock layers record time (lower = older). A fossil found only in an older layer and absent from younger layers indicates the organism disappeared before the younger layers were deposited, i.e., it went extinct in that region.