[Campbell Biology P.743] According to the phylogenetic diagram and accompanying text, which ... | Practice Question

According to the phylogenetic diagram and accompanying text, which of the following accurately describes the relationship of Bilateria to other animal groups?

  • A: Bilateria is an ancient clade that includes Porifera and Cnidaria as its earliest diverging members.
  • B: All members of Bilateria exhibit radial symmetry and are diploblastic.
  • C: Lophotrochozoa, Ecdysozoa, and Deuterostomia are the three major clades within Bilateria.
  • D: The common ancestor of living bilaterians lived about 560 million years ago, coinciding with the Cambrian explosion.

Explanation

The text explicitly states: 'Molecular evidence suggests that today there are three major clades of bilaterally symmetrical animals: Lophotrochozoa, Ecdysozoa, and Deuterostomia.' This is also consistent with the provided phylogenetic tree diagram.