Geologic Time

1. the shape of trilobite head that is used for protection, stability, and fighting (2 words, no space)
4. another name for the trilobite's tail
6. "middle life" Earth era; it occurred 252 million to 66 million years ago and included dinosaurs and birds
7. the part of the trilobite made of many lenses; it allows them to see in many directions
8. the shape of trilobite head that is used for swimming, burrowing, and defense (2 words, no space)
9. this type of trilobite has large eyes and feathery "paddle" legs
10. natural fracture lines on the trilobite head; they aid in shedding of the exoskeleton (2 words, no spaces)
13. the "cheeks" of the trilobite; they are located on the dorsal side of the trilobite's head (2 words, no spaces)
15. the oldest of Earth's eras; it occurred 4.6 billion to 541 million years ago and included single-celled life and first ocean life
16. the top or back side of the trilobite's cephalon
18. another name for the trilobite's head
20. an index fossil made of three lobes

2. the trilobite's "mouth"; it is located on the ventral side of the trilobite's cephalon
3. the type of fossil used to identify and date rocks (2 words, no spaces)
4. "ancient life" Earth era; it occurred 541 million to 252 million years ago and included trilobites, fish, and first land plants
5. "recent life" Earth era; it occurred 66 million years ago to present and includes mammals and humans
11. the trilobite's "nose"; it is at the front of the trilobite's cephalon and is used to anchor the front part of the trilobite
12. the bottom/under or belly side of the trilobite's cephalon
14. this type of trilobite has small or no eyes; it scurries along land and mud using its many jointed legs
17. the part of the trilobite important for protection and when competing for food and
19. another name for the trilobite's segmented middle