The fossil record of insects has more gaps and larger gaps than the fossil record of vertebrates. From the following list, choose all the reasons why this is so:
A. Insects were smaller than vertebrates.
B. Insect habitats were not in places where fossils formed.
C. Insects had fewer large, hard body parts that could fossilize the way vertebrates did.
D. Insects left less trace evidence that could fossilize than did vertebrates.
E. There were fewer insects than vertebrates throughout geological history.