Chapter 33, Problem 7TYU

Evolution connection • Interpret thf data Draw a phylogenetic tree of Bilateria that includes the ten phyla of bilaterians discussed in detail in this chapter. Label eath brauch that leads to a phylum with a C, P, ur A, depending on whether members of thc phylum are coelomates (C), pseudocoelomutes (P), or acoelomatos (A). Use your labeled tree to answer the following questions:

1. (a) For each of the threc major clades of bilaterians, what (if anything) can be inferred about whether the common ancestor of the clade had a true coelom?
2. (b) To what extent has the presence of a true coelom in animals changed over the course of evolution?