fossils. big ideas fossils give evidence of evolution. fossils of original preservation fossils with...

Fossils

Big Ideas

• Fossils give evidence of evolution.

• Fossils of original preservation

• Fossils with altered hard parts

• Index fossils

• Molds and casts

• Trace fossils

Evolution

• The change in populations as a result of an altered environment.

About 12 million years ago, a volcano in southwest Idaho spread a blanket of ash over a very large area. One or two feet of this powdered glass covered the flat savannah-like grasslands of northeastern Nebraska.Most of the animals which lived here survived the actual ashfall, but as they continued to graze on the ash covered grasses, their lungs began to fill up with the abrasive powder. Soon their lungs became severely damaged and they began to die. The smaller animals died first (smaller lung capacities) and finally, after perhaps three to five weeks, the last of the rhinos perished. Their bodies were quickly covered by the blowing and drifting ash.Undisturbed except by an occasional scavenging meat-eater, the skeletons of these animals are preserved in their death positions, complete with evidence of their last meals in their mouths and stomachs and their last steps preserved in the sandstone below.

Original preservation

• Tar• Freezing• Amber (tree sap)• Oxygen deprivation

When this photograph was taken around 1910, the location depicted was described as "the Salt Creek oilfields, 7 miles west of Los Angeles." Today, this spot is in the middle of downtown Los Angeles.

1907 U.S. Geological Survey drawing shows how oil from underground rock layers migrates upward to fill the La Brea pits.

Don’t cry for me, for I shall live on as a fossil in 2009!

Spider preserved in Amber, or tree sap.

Bog bodies are often inadvertently damaged, as a result of peat mining efforts.

Left: English locations for bog body discoveries.

Right: A reconstruction of a bog body discovery.

As described on page 566,

Graubelle man was found in 1952 in a bog in Jutland, Denmark. He has been buried for close to 2,000 years. Imagine all that has happened, just 10 feet above him.

Another name for permineralization is petrifaction. The hard parts have been removed and replaced by rock minerals.

Index fossils tell how old the surrounding rocks are, if one knows how old the fossil is.

Good index fossils

1. Are very widespread.

2. Existed during a short period of time on Earth.

3. Are of a life form that was very abundant.

4. Unique

A mold is when the organism has died, and left only an impression of itself for us to remember it by.

A CAST is when the MOLD fills in with sediment.

This flattened fossil cast of the Sigillaria tree was found in the roof of an underground coal mine-- lodged in the base of a small sandstone channel that marks the boundary of a meandering stream that flowed 300+ million years ago along an ancient delta that existed then.

Trace fossils are just evidence of past life, like casts or molds of footprints or burrows.

Absolute age

• Relative age, compared to others• Absolute age, age in years (bce)• Tree rings• Varves• Half-life

Match up the “bar codes”, and work your way back.

Summer Heavy material falls to bottom, light material stays in suspension.

Winter There is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Again, the heavy material falls to bottom, light material stays in suspension.

Winter Again, there is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Heavy material falls to bottom, light material stays in suspension.

Winter There is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Again, the heavy material falls to bottom, light material stays in suspension.

Winter Again, there is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Heavy material falls to bottom, light material stays in suspension.

Winter There is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Again, the heavy material falls to bottom, light material stays in suspension.

Winter Again, there is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Heavy material falls to bottom, light material stays in suspension.

Winter There is ice on the lake, so lighter material can settle out, heavy material has already done so.

Summer Again, the heavy material falls to bottom, light material stays in suspension.

Winter Again, there is ice on the lake, so lighter material can settle out, heavy material has already done so.

Varves are very similar to tree rings, with the dark being winter floods, and the light being the summer floodings.

How old are these things (REALLY). Is there any way to tell almost exactly how old something is?

How old are these things (REALLY). Is there any way to tell almost exactly how old something is?

YES!! It is radiometric dating!! We will be looking at Carbon-14 dating for now.

How old are these things (REALLY). Is there any way to tell almost exactly how old something is?

YES!! It is radiometric dating!! We will be looking at Carbon-14 dating for now.

To understand this, you will have to remember a few things. Much of this will be review.

1. What is in an atom (review only)

2. What an element is (review only)

3. How an element changes from one to another

4. What a half-life is

How old are these things (REALLY). Is there any way to tell almost exactly how old something is?

YES!! It is radiometric dating!! We will be looking at Carbon-14 dating for now.

To understand this, you will have to remember a few things. Much of this will be review.

1. What is in an atom (review only)

An atom is made up of three things, at most.

Protons~ positively charged particle in the nucleus. THE NUMBER OF PROTONS DETERMINES WHAT THE ELEMENT IS.

Examples

Element Name Number of Protons Atomic Number NeutronsAtomic Mass

Hydrogen One One 0,1,2 or 3 1,2,3 or 4

Nitrogen Seven Seven 6,7,8,9 or 1013,14,15,16 or 17

Carbon Six Six 6,7,8,9 or 1012,13,14,15, or 16

Protons~ positively charged particle in the nucleus. THE NUMBER OF PROTONS DETERMINES WHAT THE ELEMENT IS.

Examples

Element Name Number of Protons Atomic Number NeutronsAtomic Mass

Hydrogen One One 0,1,2 or 3 1,2,3 or 4

Nitrogen Seven Seven 6,7,8,9 or 1013,14,15,16 or 17

Carbon Six Six 6,7,8,9 or 1012,13,14,15, or 16

Carbon - 14 will have 14 "things" in its nucleus.

Carbon - 14 must still have 6 protons in its nucleus.

Carbon - 14 must have 8 neutrons to make it "14". (6 protons + 8 neutrons = 14 nucleotides)

Carbon - 14

Protons 6

Neutrons ?

Nucleotides 14

Carbon - 14

Protons 6

Neutrons 8

Nucleotides 14

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons ?

Nucleotides 14 Nucleotides14

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

a. Each 5,730 years 1/2 of all of the C-14 in the world will change into Nitrogen - 14.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

a. Each 5,730 years 1/2 of all of the C-14 in the world will change into Nitrgen - 14.

b. Unless more is made, 1/2 of all the C-14 in the world will disappear each 5,730 years.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

a. Each 5,730 years 1/2 of all of the C-14 in the world will change into Nitrgen - 14.

b. Unless more is made, 1/2 of all the C-14 in the world will disappear each 5,730 years.

c. 5,730 years is the half-life of Carbon-14.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

a. Each 5,730 years 1/2 of all of the C-14 in the world will change into Nitrgen - 14.

b. Unless more is made, 1/2 of all the C-14 in the world will disappear each 5,730 years.

c. 5,730 years is the half-life of Carbon-14.

d. Other elements have other half-lives.

Carbon - 14 Nitrogen - 14

Protons 6 Protons 7

Neutrons 8 Neutrons 7

Nucleotides 14 Nucleotides14

The only difference is that one neutron is a proton. That is all. Fin. No mas. Zip.1. On average, 1/2 of all Carbon - 14 will do just that each 5,730 years.

a. Each 5,730 years 1/2 of all of the C-14 in the world will change into Nitrgen - 14.

b. Unless more is made, 1/2 of all the C-14 in the world will disappear each 5,730 years.

c. 5,730 years is the half-life of Carbon-14.

d. Other elements have other half-lives.

2. The Sun helps create more Carbon-14, so the amount in the environment remains very constant.

The half life of a radioactive isotope represents the time that is needed for half of the unstable atoms of a given radio-isotope to decay. Uranium-238 has a half life in the billions of years and roentgenium has a half life of less than one second.

Isotope Half-life Use

Carbon 11 20 minutes Agriculture

Iodine-131 8 days Medical therapy

Krypton-85 11 years Industry

Cesium-137 30 years Treat cancers,

Sterilize garbage and medicinal wastes

Calibrate equipment

Irradiate blood for transfusions

Carbon-14 5730 years Test new drugs for harmful by-products

Carbon dating of ancient artifacts

Iodine-129 15.7 million years Check radioactivity counters at in-vitro diagnostic labs

Uranium-238 4.5 billion years Color brighteners in dental fixtures; dating old rocks

KEY POINTS

1. Each living things has the same percentage of C-14 as each other living thing.

2. After death, the C-14 turns into N-14 at a pretty constant rate.

3. About 50% of the existing C-14 turns into N-14, each 5,730 years.

4. All radioactive elements have half lives.

Magna Carta, about

Magna Carta, about

Early Romans, about

Magna Carta, about

Early Romans, about

North America is populated Ice Age in full

swing

Magna Carta, about

Early Romans, about

North America is populated Ice Age in full

swing

Not really much good out here, because the curve and "x" axis are almost parallel.

Time in millions of years

Percentage of an imaginary radioactive isotope, similar to Uranium - 238, with a half life 1000x that of C-14

Solar system

Earth

Life

Humans

Big Bang; time does not exist

He was found

1. With expensive furs and shoes

2. With bronze points for his arrows

3. With a full belly of food

4. With food in a pack on his back

5. With a probable, fatal arrow wound in his back. The arrow was probably shot from about 20 to 30 feet away

6. He probably died high in the mountains

7. Who killed him, and why.