Prehistoric Giants

5. animals that live part of their lives in water and part on land
6. long, flexible armlike growths on an animal that the animal uses to fell things, to hold things, or to move
8. of or relating to the sea
9. animals that eat only plants
11. a period in Earth's history when ice sheets covered large areas of land
13. animals that do not have backbones
16. large divisions of time in Earth's history: Paleozoic, Mesozoic, and Cenozoic
17. divisions of time - such as Permian, Jurassic, and Tertiary - that make up larger eras of time in Earth's history

1. any animal whose body has a hard covering and jointed legs, including insects, crabs, lobsters, spiders, and centipedes
2. common prehistoric sea animals that were covered with a soft shell
3. a chemical in cells that has instructions for the formation and growth of new cells and new organisms
4. scientists who study fossils to learn about animals and plants that lived long ago
7. of or relating to the time before writing was invented, about 6,000 years ago
10. the kind of place where a plant or animal lives in nature
12. animals that hunt and eat other animals
14. no longer living
15. a group of organisms that have most things in common and can make new organisms of the same kind