The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D.

Figure 22.1
-If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?
A) A
B) B
C) C
D) D

Question

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
  
Figure 22.1
-If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?
A) A 
B) B 
C) C 
D) D

Quizplus · Accepted Answer

In stratigraphy, the principle of superposition states that in an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. Therefore, if fossils of two closely related species are found in a particular stratum, their most recent common ancestor would most likely be found in a lower (older) stratum, which is indicated by option C.

The Following Questions Refer to Figure 22