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.
2. Based on the information presented, which of the following genera most likely shared an MRCA that had a hole in its hip socket and three-toed hind feet?
Your Answer is
Correct Answer is F
Explanation
Looking at Table 1, both Archaeopteryx and Allosaurus are + in these two characteristics, and both have these two characteristics, so their MRCA is also most likely to have these two characteristics.