Biology Ch. 12

1. a category of mammals with flexible hands and feet, forward-looking eyes, and enlarged brains
2. 251 to 65 million years ago, also known as the Age of the Reptiles
4. the early part of the Paleozoic era in which a huge diversity of animal species evolved
5. several million years
8. 65 million years ago to today
10. the oldest living and smallest primate group
11. orangutans, chimpanzees, gorillas, and humans
12. tens to hundreds of millions of years
16. compares the placement of fossils of the organism with fossils in other layers of rock
18. the amount of time it takes for half of the isotopes in a sample to decay
19. bacteria that can carry out photosynthesis

1. 542 to 251 million years ago
3. RNA molecules that can catalyze specific chemical reactions
6. tens of millions of years
7. animals that can walk on two legs
9. uses the natural decay rate of unstable isotopes to calculate the material's age
13. a relationship in which one organism lives within the body of another
14. atoms of an element that have the same number of protons but a different number of neutrons
15. a cloud of gas and dust in space
17. the human-like primates