Across
- 2. characteristics
- 4. clock
- 6. Theory
- 8. equilibrium Ectoderm
- 12. Selection
- 13. genes
- 14. of the fittest
- 15. record
- 16. evolution
- 18. structure
- 19. group
- 20. Timescale
- 21. Clock
Down
- 1. nomenclature
- 3. for existence
- 5. descent
- 7. radiation
- 9. Darwin
- 10. structure
- 11. in genes
- 17. structure