[Campbell Biology P.697] Based on the information in Figure 30.14b and its caption, would th... | Practice Question

Based on the information in Figure 30.14b and its caption, would the branching order of the phylogeny necessarily have to be redrawn if a 150-million-year-old fossil monocot were discovered?

  • A: Yes, because a 150-million-year-old monocot fossil would predate the estimated origin of angiosperms (140 million years ago), requiring a re-evaluation of the entire angiosperm phylogeny's timeline and potentially the branching order of early diverging lineages.
  • B: No, because the discovery of an older fossil only confirms the existence of the group and does not alter the relative branching order of existing clades.
  • C: Yes, because monocots are considered one of the most derived groups of angiosperms, and an early fossil would contradict this evolutionary progression.
  • D: No, because the phylogenetic tree in Figure 30.14b primarily represents extant relationships, and fossil discoveries are integrated separately.

Explanation

The caption for Figure 30.14b states that 'Angiosperms originated about 140 million years ago.' If a 150-million-year-old monocot fossil were discovered, it would mean that angiosperms, including monocots, must have originated at least 150 million years ago. This directly contradicts the current estimated origin time and would necessitate a re-evaluation and redrawing of the entire angiosperm phylogeny's timeline and potentially the relative branching order of its earliest diverging lineages, as the common ancestor of all living angiosperms would need to be pushed back in time.