Across
- 1. Hypothesized stage in the origin of Earth's first life forms when membrane-enclosed sacs formed around organic molecules
- 4. Layered rocks resulting from prokaryotic activities that bonded thin films of sediment together
- 5. When many new species arise to fill in new or vacant ecological roles in their communities (two words)
- 6. Refers to a master control gene that determines identity of body structures during organismal development
- 10. Supercontinent that formed when landmasses came together near the end of the Paleozoic
- 11. Theory that complex organelles, e.g., mitochondria and chloroplasts, started as prokaryotic cells engulfed by an ancestral cell
- 16. Broad pattern of evolutionary change beyond the population and species levels
- 17. Method for determining absolute age based on half-life of radioactive isotopes (two words)
- 18. Geological era beginning approximately 250 million-years ago when mammals first appeared and dinosaurs flourished
Down
- 2. Geological period beginning approximately 540 milion-years ago and marking the radiation of the earliest animal forms
- 3. Geological eon which includes the Paleozoic, Mesozoic, and Cenozoic eras
- 7. Permanent disappearance of a great many species in a relatively short time (two words)
- 8. Geological era beginning approximately 65 million-years ago and coinciding with the prominence of mammals in the fossil record
- 9. Geological eon during which the oldest known fossils of eukaryotic cells and soft-bodied animals and algae appear
- 12. Geological era beginning approximately 540 million-years ago and ending approximately 250 million-years ago
- 13. Referring to Earth's crustal plates
- 14. Geological eon marking a time when no life forms existed on Earth
- 15. Any RNA molecule that functions as an enzyme