human origins

week 10 notes

paleontology

study of extinct organisms based on fossilized remains

paleoanthropology

study of fossil record of ancestral humans and primate kin

taphonomy

study of what happens to the remains of an animals from its time of death to the time it is discovered (biological and geological processes)

what can fossils tell us?

• the fossil species

• how old the fossil is and it’s individual age

• reconstruct how the organism had lived

stratigraphy

the study of the order of rock layers (strata) and the sequence of events that they reflect

the principles of stratigraphy

-principle of original horizontality

-principle of superposition

-principle of cross-cutting relationships

relative dating

the age of fossil determined in comparison to another material found above and below it

relative dating techniques

stratigraphy

lithostratigraphy

tephrostratigraphy

biostratigraphy

chemical methods

chronometric dating techniques

radiometric methods - use of radioactive decay of isotopes to estimate age

isotopes - variant of element; differ in atomic weight and number of neutrons in the nucleus

half-life - time it takes for 1/2 of the original amount of unstable isotope to decay into stable form

radiocarbon dating

potassium-argon dating

radiocarbon dating

• c-14 is unstable

• half-life of carbon-14 is 5,730 years

• date range = <40,000 years

potassium-argon dating (K-Ar)

• decay of 40k to 40 Ar

• K-bearing materials

• can date fossils millions of years old

• 1.3 billion years = ½ life

• date range = 10,000 - 4.5 billion years

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