Paleontology/Evolution

Relative time

Places events in a sequence

Absolute Time

Identifies the actual date of an event

Half-life

The time it takes for ½ the atoms of a radioactive isotope to decay.

Dendrochronology

Tree ring data

Radiometric dating

The use of radioactive isotopes (elements) to measure time.

Varves

Yearly layers of sediment in lakes

4.6 by.

Age of earth

3.7 by.

Oldest fossils

65 my.

End of Mesozoic

200,000 to present

Modern humans

Precambrian

Earths formation. 4.6 billion years. 90% of earth’s history. Oldest fossil 3.7 by. Chemosynthetic bacteria. Few fossils.

Paleozoic era

Great diversity of life. Lots of fossils. 1st land plants, fish, amphibians, reptiles. Major mass extinction 90% of life.

Mesozoic era

Large reptiles- Dinosaur. Mild climate. Pangea breaks apart. Mammals. Mesozoic extinction 50%, asteroid impact.

Cenozoic era

Mammals. evolution of hominids/bipedalism(up right walking)

Ardipithecus ramidus

The oldest bipedal ape.

Australopithecus afarensis

A bipedal chimp-like. “Lucy”. Oldest ancestor ?

Homo erectus

First hominid to spread out of Africa. First to use fire and tools.

Homo neanderthal

A version of human. Out competed by modern

humans?

Homo sapiens

Modern people.

Original Remains

(un-altered) Parts of the organism remain in the fossil.

Molds

An impression of an organism

Casts

A 3d representation of the organism

Mineral replacement

Remains are replaced by minerals

Amber

Fossil tree sap. (insects)

Trace

Tracks, burrows and droppings

Carbon

Black carbon outline of organism. leaves common, coal.

Pseudo Fossils

Not fossils, mineral deposits which look like ferns.

Index Fossils

Fossils used to age date rock layers. Easy identified, widespread, short period of time.

Stromatolites

Blue-green algae. First oxygen maker

Human migrations

1. 50,000 yrs ago to Australia

2. 35,000 yrs ago to central Asia, then the rest of the world.

Fossil

Any evidence of past life.

Biological evolution

Any change in the gene pool of a population.

Natural selection

The process in nature that results in the most fit organisms producing offspring.

Charles Darwin

Founder of modern evolutionary theory

Steps of natural selection

1. Organisms overproduce offspring.

2. There are variations within populations.

3. Individuals with favorable variations survive

   and reproduce, passing those traits to the next

   generation.

4. Gradually over time these offspring make up

   a larger % of the population.

Gene pool

Shared genes of a population.

Speciation

The development of new species

Steps of speciation

1. Founding fathers and mothers

2. Separation of populations

3. Reproductive Isolation

4. Natural Selection

5. Adaptive Radiation

Punctuated Equilibrium

Long stable periods interrupted by quick periods of change.

Reproductive isolation

Populations are separated and cannot interbreed.

Gradualism

Evolution occurs slowly over time