Earth and Space

4. A group of similar animals capable of breeding with each other
5. Period of time in the Paleozoic Era, ending in the first mass extinction
7. Force applied on an object
8. Expert on prehistoric life
9. Energy found coming from the sky in bolts
12. Process in which rock is removed from the earth's surface by wind or water
15. Large period of time. There are only three in earth's history
16. Period of time ending in the disappearance of 70% of marine species
17. Period whos mass extinction caused the disappearance of 96% or marine species and 75% of all land species
18. Petrified bones
19. Large decrease in the amount of life, 5 of these have occurred in earth's history

1. All vertebrates have these
2. The mass extinction at the end of this period created the K/T boundary
3. A change made to an organism to suit a new environment
4. Type of rock fossils are most commonly found in
6. Essential for the emergence of life, destructive if you live in a certain city in italy
10. First period of the Mesozoic Era
11. Layer of rock with the came characteristics
13. Star that is a possible energy source in the emergence of life on earth
14. Conversion of organic material into stone