1.some of the fossils that have been found from before the cambrian explosion are embryos this suggests that the organisms these fossils belong to
a. have bilateral symmetry
b. reproduce asexually
c. exhibit cephalization
d. reproduce sexually
2. most of the body features found in invertebrates evolved during which of the following periods?
a. jurassic
b. cambrian
c. cretaceous
d. permian
3. a marine biologist exploring a deep sea trench locates a new species of soft bodied creatures with an unfamiliar shape. he is able to determine that the creature is a mollusk because it has
a. bilateral symmetry
b. body segmentation
c. an internal shell
d. am internal skeleton