Warm Up What is the difference between a scientific theory and a “common language” theory? Who proposed that organisms changed over time by trying to improve their own traits and passing the improved traits on? Who came up with the idea of natural selection? What is evidence? Who uses it?

LET’S PLAY… THE DATING GAME!

If you were a jellyfish, would you form a fossil? For our 1st question… If you were a jellyfish, would you form a fossil?

Fossil: preserved remains Of once-living organisms REMEMBER… Fossil: preserved remains Of once-living organisms

Fossilization Facts Hard parts of organisms are more likely to be preserved than soft parts. Soft parts are likely to decay or be eaten by other organisms. (Because of this, soft-bodied creatures such as jellyfish may not be fossilized at all) Buried organisms are more likely to be fossilized because it minimizes the decay, consumption, and destruction of the remains.

2nd Question: If you were a fossil, what kind of fossil would you be? Body Fossil: preserved body structure Ex: Bones Trace Fossil: evidence that an organism existed other than a body structure Ex: tracks, trails, footprints

Petoskey Stone (ancient coral: hexagonaria ~ 350 mya) Body or Trace?

Number 3… Are you a relative dater or an absolute dater? WHAT?? Relative dating: Gives age of a fossil based on its location in sedimentary (layered) rock. (gives age relative to other fossils) Absolute dating: Gives the actual age of a fossil based on the amount of radioactive elements in it. (More exact, gives absolute age)

Relative Dating Fossils form in sedimentary rock – As time passes, layers of rock form on top of previous layers http://www.carleton.ca/~tpatters/teaching/climatechange/rocks/rocks11.gif

Radioactive Dating AKA - Carbon dating – a way finding the ages of rocks and fossils based on the half-life of carbon (or other elements) Half life: Amount of time for half of the atoms in a sample to undergo radioactive decay (The nucleus of the atoms change – they lose protons and/or neutrons) Scientist compare the amount of specific elements with an known half-life to determine the date when the organism was around.

Radioactive Dating – info for our lab Carbon 14 decays into Nitrogen 14 (5730 yrs) Uranium 238 decays into Lead 206 (4.5 billion years) Potassium 40 decays into Argon 40 (1.3 billion years)

The Fossil Record (add def. to bottom of notes) A collection of all the fossils that have ever been found on earth provides info about the evolutionary history of organisms Important note – Evolution doesn’t follow a straight line to a goal… Not all horse like species evolved like this!

Fossils of species that became EXTINCT – species that no longer exist – help scientist reconstruct the past

As a fossil, why are you important to scientists? gave Darwin evidence that earth is OLD and that small changes over a long period of time can add up to substantial changes in organisms let scientists to see extinction in different species Let scientists compare fossils to living organisms to determine how closely related different species are

Brain Pop!

Answer Fossil questions on the bottom of this page using your textbook

Tonight’s HW: How do I become a fossil? What are some things I can do that would improve my chances of becoming a fossil after I die? Read article – write 5 (or more) bullet points of ways to improve the chances of becoming a fossil