1. Evolution Notes: Part 2

2. Fossils
Fossils are the remains or imprints of once-living organisms found in layers of rock. They are formed when layers of sand, dust or soils are deposited in an orderly fashion on top of older layers.
When these sediments are compacted, they bury the things lying beneath and create sedimentary rock. 

3. Fossils
Fossil Record: a historical timeline of life indicated by physical similarities of fossils and their estimated age. In undisturbed areas, older fossils are assumed to be buried beneath newer fossils. 

4. Types of Dating
Relative Dating: matching rock layers with  fossils to determine the approximate age of the fossil based on where it is found in a geologic column. 
Radiometric Dating: determining the approximate age of rock by analyzing certain radioactive substances in rocks and their known rates of decay. 

5. Vestigial Structures 
Vestigial Structures: body structure that has no purpose in a present day organism, but was probably useful to an ancestor.
Examples:
Pelvic bone in whale
Appendix in humans

6. Homologous Structures
Homologous Structures: body parts from organisms of different species that are similar in structure and suggest the organisms share a common ancestor.
Example

7. Evidence for Evolution
DNA- all organisms have DNA and scientists believe that the more similar the DNA between organisms, the more closely related they are. The fact that all organisms have DNA indicates a common ancestor.