Passage I

Table 1 indicates the presence or absence of 6 traits in 7 dinosaur genera (genera is the plural of genus).

Figure 1 is a cladogram (a diagram showing evolutionary relationships) for these dinosaur genera based on the 6 traits in Table 1. Figure 1 also includes 6 dinosaurs (A-F) at 6 nodes (branch points).The dinosaur at each node represents the most recent common ancestor (MRCA) of the dinosaur genera extending upward from that node. Each MRCA had all traits that were shared by all of the genera extending upward from it.

Table 1 and Figure 1 adapted from Neil A. Campbell, Biology, 4th ed. @1996 by The Benjamin/Cummings Publishing Company, lnc.

Table 2 indicates when each of the 7 dinosaur genera in Table 1 existed.

4. Based on the information presented, which of the following dinosaurs most likely had an unequal enamel layer on its teeth?

Answer and Explanation

Your Answer is

Correct Answer is J

Explanation

It can be seen from Table 1 that Parasaurolophus, Pachycephalosaurus, and Triceratops all have unequal enamel layer on teeth, and the MRCA of the three of them is Dinosaur E, so Dinosaur E should also have unequal enamel layer on teeth, then Dinosaur As a descendant of E, F should also have this feature.