Which of the Following Characteristics Represents the Oldest Branch Point

Question

Which of the following characteristics represents the oldest branch point in animal phylogeny?
A) radial or bilateral symmetry
B) diploblastic or triploblastic embryos
C) true tissues or no tissues
D) a body cavity or no body cavity

Accepted Answer

The oldest branch point in animal phylogeny is the distinction between animals with true tissues (Eumetazoa) and those without true tissues (such as sponges, Phylum Porifera). This fundamental difference represents the earliest divergence in the animal kingdom.