What do all craniates have that earlier chordates did not have?
A) brain
B) vertebrae
C) cartilaginous pipe surrounding notochord
D) partial or complete skull
E) bone

Question

Quizplus · Accepted Answer

Craniates have a partial or complete skull, which is a structure that earlier chordates did not have. This is why they are called "craniates" in the first place.

Answer: A, B, D, E
 All of these characteristics distinguish craniates from earlier chordates. They have a brain, vertebrae, a partial or complete skull, and bone (at least some species do). However, choice D is the most specific and accurate answer, as it specifically mentions the defining characteristic of craniates.

What Do All Craniates Have That Earlier Chordates Did Not