[Campbell Biology P.733] According to the 'Future Directions in Animal Systematics' section,... | Practice Question
According to the 'Future Directions in Animal Systematics' section, which statement best describes the current understanding and debate regarding basal metazoans?
A: All recent phylogenomic analyses conclusively place ctenophores as basal metazoans due to their tissue presence.
B: Sponges are considered basal metazoans because they share a common ancestor with choanoflagellates and possess tissues.
C: While many researchers conclude sponges are basal metazoans supported by evidence like fossil steroids, other studies place comb jellies (ctenophores) at the base of the animal tree, leading to an intriguing but controversial hypothesis.
D: The debate about basal metazoans has been fully resolved, with molecular clock analyses definitively confirming sponges.
Explanation
The text states: 'Many researchers have concluded that sponges are basal metazoans see Figure 32.11 . This conclusion was supported in a 2017 phylogenomic analysis, but several other studies have placed the comb jellies phylum Ctenophora at the base of the animal tree.' It then refers to this as 'an intriguing but controversial hypothesis.'