Biology 8th Edition by Kenneth Mason ,Jonathan Losos,Susan Singer,Peter Raven,George Johnson

Exercise 4

List the synapomorphy and the taxa defi ned by that synapomorphy for the groups pictured in figure 23.2. Name each group defined by a set of synapomorphies in a way that might be construed as informative about what kind of characters define the group.
Figure 23.2 A cladogram. a. Morphological data for a group of seven vertebrates are tab ulated. A "1" indicates possession of the derived character state, and a "0" indicates possession of the ancestral character state (note that the derived state for character "no tail" is the absence of a tail; for all other traits, absence of the trait is the ancestral character state). b. A tree, or cladogram, diagrams the relationships among the organisms based on the presence of derived characters. The derived characters between the cladogram branch points are shared by all organisms above the branch points and are not present in any below them. The outgroup (in this case, the lamprey) does not possess any of the derived characters.