The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups-Lophotrochozoa and Ecdysozoa. What does this finding suggest?
A) These two subgroups have a common ancestor that exhibited deuterostome development.
B) Division of these two groups occurred before the protostome developmental sequence.
C) Division of these two groups occurred after the protostome developmental sequence appeared.
D) The lophotrochozoans are monophyletic.

Question

Quizplus · Accepted Answer

The finding suggests that the division into Lophotrochozoa and Ecdysozoa occurred after the establishment of the protostome developmental sequence, indicating they share a common ancestor that already exhibited this form of development.

The Protostome Developmental Sequence Arose Just Once in Evolutionary History