Rock layers containing extensive fossils of organisms with hard parts represent only about 12% of geologic time.

Question

Quizplus · Accepted Answer

Most of Earth's geologic history is recorded in rocks containing fossils of organisms with soft bodies, which are less likely to fossilize. Rocks with extensive fossils of hard-part organisms represent a smaller fraction of the geologic record, making the 12% figure accurate for those specific layers.

Rock Layers Containing Extensive Fossils of Organisms with Hard Parts