science

1. Age of the Dinosaurs
5. Earth's current geological era
8. extinct marine arthropods that form the class Trilobita
10. the placement of one thing on top of another
13. bones, scales, teeth, and other hard parts of fish recovered from archaeological sites, fossil beds, or organic waste.
15. a major geological era lasting from about 541 to 252 million years ago

2. hard protective outer layer created by sea organisms
3. extinct, shelled marine mollusk belonging to the cephalopod group
4. fossilized remains of prehistoric reptiles that lived millions of years ago.
6. the length of time that a person has lived or a thing has existed
7. any preserved remnant, impression, or trace of an animal, plant, or other organism from a past geologic age
9. Earth's structure is the inner core
11. the science of determining if one rock layer, fossil, or geologic event is older or younger than another without finding its exact numerical age in years
12. the time, events, and existence that happened before the present moment
14. eukaryotic organisms that constitute the kingdom Plantae.