Issues Test 3. Lets kill it.

List the 4 kinds of fossils found in the Pennsylvanian and Permian.

- Invertebrates - Amphibians - Reptile fossil footprints - Fossil land plants

What kinds of habitats were occupied by the majority of creatures living in the Paleozoic Biomes?

- Oceans - Shallow seas - Some lived in low lying bogs and jungles

List 3 radiometric dating methods other than 14C that are commonly used.

- Potassium-argon - Uranium/thorium-lead -Rubidium/strontium

When magma from within the earth comes toward the surface to form a new deposit, why must it not mix with older rock? Why must there be no exchange of parent or daughter elements with fluids that move through the rock?

- Because that could change its apparent age. - If there is such an exchange, the "clocks" of the rock will be inaccurate because the parent/daughter ratio will be the result of something other than the amount of time that has passed.

How is a time calibration provided for the biostratigraphic scale (the scale of ages for the different layers of rocks and fossils)? How reliable are these radiometric dates?

- By using radiometric methods to date minerals near the fossils. - They can be uncertain by several percentage points, even for the most reliable dates.

What did William Smith observe as he supervised the building of the Somerset canal in England? What was he able to predict based on this discovery? What is this discovery called?

- He observed that the same kinds of fossils always occurred in the same layers of rocks on in specific sequences. - He could predict the type of deposited above or below any layer he was studying. - The Law of Faunal Succession.

When fossil-bearing rocks do not contain the correct minerals for precise dating with radiometric dating methods, how is the age of the deposits determined? Describe how this works. What is the limitation of this method?

- Primarily by biostratigraphy - The fossils in the rock and in the formation above and below them are compared with the sequence of fossils in other locations to see where they fit in the sequence. - The fossils found in the rock can only be used for comparing the sequence of rocks in different locations and do not indicate the age of the rocks in years .

What are living fossils? Give 2 examples.

- Species that show little or no measurable morphological change over extended periods. - Ex. ginkgo leaves, stromatolites, horseshoe crabs.

What did Murchison find about fossil communities as he worked his way up the rock layers? What was found in each of Murchison's "formations"? What did Murchison do that established the Law of Faunal Succession as a way to correlate rock layers world-wide?

- That the fossil communities changed (as he worked his way up the rock layers). - Each formation contained distinct fossil communities. - He studied the fossil and rock layers in different parts of the world. He worked out the sequence of rocks below the coal bearing layers in Wales. He went to other areas and found the same fossil communities in the same order. And then found new communities above them in other places.

What does the presence of 14C in many samples throughout the Phanerozoic indicate? Why should most of these samples not contain any 14C?

- That the samples are all younger than 70,000 years. - Because the radiometric time scale would provide more than enough time for all the 14C to be lost through decay.

What is the source of 14C? List 2 concepts

1. 14C originates in the upper atmosphere when cosmic rays strike nitrogen molecules. 2. This leads to the change of nitrogen atoms into 14C

What is the pattern of extinct versus modern groups that are found in the geologic column? List 2 concepts.

1. A high percentage of fossils in the Paleozoic are in extinct groups 2. The percentage of modern groups increases toward the upper part of the fossil record

What does it mean that the radiometric clock was set to zero when the rock was deposited in its present location? List 2 concepts

1. All previously existing daughter products escaped at that time. 2. Or the initial amount of daughter products can be estimated based on mathematical calculations from the data.

How do short-age geologists interpret the Phanerozoic? List 2 concepts

1. At least from the beginning of the Cambrian, the geologic record has formed very rapidly, not over the long evolutionary time scale. 2. Part of it is a record of activity during a global catastrophe.

Why does the amount of 14C in a plant or animal diminish after it dies? List 2 concepts

1. Because it no longer takes in fresh 14C. 2. The 14C that it contains gradually diminishes as it decays to nitrogen.

How are most fossils dated using these other radiometric dating methods? List 2 concepts

1. By dating a layer of lava or other igneous rock near the fossil . 2. Using that date to estimate the age of the fossil-bearing sediments.

What 3 ideas were the reasons for Sir Charles Lyell subdividing the Tertiary into "Epoch"?

1. His main purpose was to advance the idea of "uniformitarianism" 2. He was directly challenging the idea of "catastrophism" and the Biblical Noah's Flood. 3. He wanted to show that geological processes happened slowly over long time intervals.

How can we determine the length of time since the organism died? List 3 concepts

1. Measure the number of radioactive disintegrations per minute in standard amount of dead tissue. 2. Compare it with the decay curve for 14C. 3. Make certain assumptions.

What did Gould and Eldrege propose.(2 concepts) What did they call their theory?

1. That stasis is a real pattern in the fossil record. 2. That most morphological change occurs during speciation. - The theory of punctuated equilibrium (but it does not explain it. They still claim incompleteness of fossil record per Lee)

What needs to be true in order for radiometric dating of rocks to be accurate? List 2 concepts

1. The assumptions of the method must be valid 2. The rock must meet the conditions for valid use of the dating method.

What would happen if some percentage of old daughter products were not lost when a new rock formation was deposited? List 2 concepts

1. The clock would not be set to zero. 2. The rock will date much older than it really is.

What are the 4 assumptions upon which the accuracy of these other radiometric dating methods depend?

1. The decay rate has always been constant 2. The rock has remained a closed system with no chemical exchange with the surrounding medium 3. The radiometric clock was set to zero when the rock was deposited in its present location. 4. The parent-daughter ratios were caused only by radioactive decay of parent to daughter over time.

What are 4 assumptions upon which the accuracy of carbon 14 dates is dependent?

1. The decay rate has always been constant. 2. The amount of CO2 in the atmosphere has always been constant. 3. The amount of cosmic rays entering our atmosphere has been constant. 4. Many plants take in 14C and 12C unselectively, without preference for 12C.

How could biome succession explain the overall order of fossil found in the geologic column?

1. The first biomes to be buried in a flood model would be marine biomes. This correlates with the marine fossil communities at the bottom of the geologic column. 2. If reptiles, dinosaurs and small mammals lived in a cooler biome at higher altitude, one would expect to find their fossil community above the marine fossil communities and below the mammal fossil communities. This correlates with what is found in the geologic column. 3. As the flood waters continued to rise, the biomes from higher, cooler altitudes would then be buried, which would likely be mammal communities. This corresponds with the order found in the geologic column .

What is an isochron and how is it plotted? List 2 concepts How is an isochron used to give the presumed age of the rock at the time it was deposited?

1. The isotopic ratios from many samples of a given rock are plotted on the graph, and a line is drawn through them. 2. If the data point fall on a straight line on the graph, it is called an isochron. - The slope of the line and the position where it meets the vertical axis are entered into a formula that gives the presumed age of the rock at the time it was deposited.

List 2 factors that determine the radiometric date of a rock.

1. The process of radiometric dating 2. The history experienced by the rock

List 2 observations about Mesozoic birds and mammals

1. They are not common 2. They all represent extinct groups

How does 14C become incorporated into carbon dioxide 14CO2?

14C combines with oxygen to form carbon dioxide.

What % of fossil species found in the Eocene were modern species (as opposed to extinct species)? What % of fossil species found in the Miocene were modern species? What % of fossil species in the Pliocene were modern species?

3% 20% 90%

How many mass extinctions have occurred during the Phanerozoic?

5 (the big 5)

What is one half life of 14C?

5,730 years

How many species are estimated to have become extinct at the end f the Cretaceous (at the K-T boundary)?

60-80%

What is a biome?

A group of plant and animal communities that live in specific environmental conditions.

According to the hypothesis of Biome Succession, what is the geologic column?

A record of Noah's flood encountering, destroying and burying the successive fossil biomes as the flood water rose.

What kind of fossils are found in the Burgress Shale in the Cambrian?

A variety of large, complex, and bilaterally symmetric formed (such as arthropods, mollusks, vertebrates, and echinoderms)

What is the half life of potassium (40K)? Note, there is an error in the book. Please look up online.

About 1300 million years = 1,300,000,000 years = 1.3 billion years

What types of animals survived?

Amphibians, crocodilians, mammals, and turtles. Few groups of birds. Insects

Where is this layer found relative to the rest of the geologic column?

At the top of the geologic column

Why is the order of events shown in the geologic column called relative geological time?

Because a layer is younger or older than another based on its relative position (on top of or underneath).

Why is Devonian sometimes called the age of fishes?

Because fish are first abundant in the Devonian

Why are these methods for dating older materials than can be dated by 14C?

Because the half lives are millions or billions of years long.

Why can 14C dating only be used to date fossils in the Upper Pleistocene or younger deposits? Note: The Pleistocene is said to have lasted from -2.5 million to 11,700 years ago.

Because the half-life is only 5,730 years it can be used only for dating fossils with a 14C age less than about 50,000 years.

Why is the ratio of 14C to 12C in the atmosphere now relatively constant?

Because the production and decay of 14c are close to equilibrium.

Why do all living animals contain 14C?

Because they eat plants that contain 14C.

What does Panel G-1 state about the complexity of the fossil biomes in the lowest layers in the geologic column as compared with modern biomes?

Biomes are no more complex today than they were in the Paleozoic.

How do we use the ratio of parent to daughter isotope in a rock sample to figure out the age of the rock?

By determining where that ratio fits on the decay curve.

Since for most methods other than 14C dating, the daughter products are not lost when a new rock forms, how can the amount of such inherited daughter products be determined?

By plotting an isochron.

How is relative geological time correlated for basins in different parts of the world?

By using fossils to correlate events (or geologic time) in different areas (or different basins).

Paleozoic - Carboniferous

Carboniferous is from the Coal Measures (coal=carbon)

Starting at the top of the geologic column, list the 3 eras and each period within the era in their correct order. See the diagram inside the back cover of the book.

Cenozoic - quaternary & tertiary Mesozoic - cretaceous, jurassic, triassic Paleozoic - permian, pennsylvanian, mississippian, devonian, silurian, ordovician, cambrian

Where are amphibians first found?

Devonian

Paleozoic - Devonian

Devonian is from Devon county (Devonshire).

What was wiped out?

Dinosaurs, pterosaurs, (flying repties), ichthyosaurs, plesiosaurs and mosasaurs (large bodied marine reptiles). Amniotes and nudists (a group of clams). 33% of land plant species in North America.

What observations did Darwin consider a problem for his theory.

Evolution in some groups seems to consist of long periods of stasis that are occasionally punctuated by speciation events that appear instantaneously in geological time. (There is no burst of speciation and morphological change (like in adaptive radiation) and no gradual change over time in response to environmental changes).

Panel G-1 states that "the geologic column represents changing communities, not increasing complexity"? What do you think evolution would predict about complexity in the layers of the geologic column?

Evolution would predict that simple organisms would be found in the lowest layers and that organisms and communities would become more complex in the upper layers of the geologic column.

What happens in the second half life?

Half of what is left will decay.

How did Darwin explain these observations?

He said it was due to the incompleteness of the fossil record.

What is a question for potassium argon radiometric dating methods?

How sure can we be that the clock has been set to zero by loss of all argon before the new rock formed?

What is a mass extinction?

Intervals in which over 60% of the species that were alive went extinct in the span of a million years = biological catastrophe.

When the rate at which radioactive decay occurs has been determined experimentally, what has been observed about this rate?

It always follows the same type of decay curve.

Radioisotopes are atoms with unstable nuclei. Through the process of radioactive decay, they emit alpha, beta, or gamma radiation and decay into more stable forms of an element. What happens over a period of time to the radioisotope, or unstable parent element?

It breaks down to form some other element (the daughter product).

What happens over time to 14C?

It decays back into nitrogen

Why is the production of 14C not affected by the amount of CO2 in the atmosphere? If the amount of CO2 in the atmosphere was higher in the past, how would this affect the concentration of 14C and the dates for the fossils? List 2 concepts.

It is produced from nitrogen, not carbon.

What is 14C dating used for? What is it NOT used for?

It is used for dating plant and animal remains. It is not used for dating rocks or minerals.

What would be required to test the assumptions of 14C dating?

It would require that we know the composition of the atmosphere and the rate of cosmic ray influx during the Pleistocene (but we cannot go back and measure those).

What kinds of animal fossils are found in the Cambrian, Ordivician, and Silurian?

Marine invertebrates and fish

Where are dinosaurs found?

Mesozoic

Where are the first flowering plant fossils found?

Middle Cretaceous (in the Mesozoic)

Can 14C dating be used for fossils that have been mineralized (like petrified wood)? Why or why not?

No, it can only be used if the organic material has NOT been replaced by minerals.

What could be an interventionist explanation for the extinction of so many species for which we find fossils, but that no longer exist today?

Noah's food.

What type of environments are found in the Paleozoic, the Mesozoic, and the Cenozoic on the continents?

Paleozoic - mostly marine environments Mesozoic - mixture of marine and terrestrial Cenozoic - mostly terrestrial

What are isotopes?

Particular forms of an element with differing number of neutrons.

Paleozoic - Permian

Permian is from the town of Perm at the base of the Ural Mountains in Russia

What kinds of fossils are found in the Cenozoic?

Plants, invertebrates, vertebrates (including birds and mammals) representing types not found lower down.

Where are human fossils found in the geologic column? Which layer?

Pleistocene deposites

What could have affected the amount of cosmic rays entering our atmosphere in the past?

Possibly the earth had a lower rate of cosmic ray bombardment due to a stronger magnetic field, and perhaps more moisture in the upper atmosphere (which would have had a limited effect).

Starting at the top, list the epochs of the Cenozoic and the periods in which they are found.

Quaternary - holocene & pleistocene Tertiary - pliocene, miocene, oligocene, eocene, paleocene

What elements are used by all radiometric dating methods other than 14C dating?

Radioactive elements that are found in minerals, not in plants or animals tissue.

What is the most serious problem faced by the short-age theory?

Radiometric dating with its 541 million years of time for the Phanerozoic.

How does that number of phyla that existed during the Cambrian compare to the diversity that is observed today?

Roughly the same

What did Werner believe about rocks? (note: these beliefs were not correct.) List the names Werner gave to the rock layers and also list the kind of rocks he believed each of the layers to be made from.

That all rocks precipitated out of seawater. Primary - Crystalline basement rocks Secondary - hard limestones Tertiary - softer sandstones Quaternary - post-flood sediments

What did he predict that paleontologists would find as they continued to study the fossil record?

That as specimen collectors grew, the apparent gaps between fossil forms caused by stasis and punctuated by sudden jumps would be filled in by forms showing gradual transitions between species.

What does the evidence show about the decay rate of 14C?

That is has always been constant.

The evidence regarding millions of years of geologic time offers serious challenges to both conventional geologic theory and short-age geology. Since the data available now do not point clearly in one direction, what does that indicate?

That many significant discoveries yet await us.

What is the Phanerozoic part of the geologic column?

The Paleozoic, mesozoic, and cenozoic

Paleozoic - Silurian

The Silures were a tribe of Celts from southern Wales

Why does Freeman say this is such a remarkable conclusion?

The earliest members of virtually all major animal lineages appeared relatively suddenly in the fossil record, at the same time in geographically distant parts of the globe.

What do all radiometric methods depend on?

The fact that some isotopes are unstable.

What is the geologic column?

The geologic column consists of layers of fossils and rocks, called strata, which were successively deposited one after another.

Where are the first mammal and bird fossils found?

The lower to middle part of the Mesozoic.

According to the conventional geology, what is the Phanerozoic considered to be?

The record of 541 million years of geologic activity and biological evolution from the bottom of the Cambrian to the present.

What was the Cambrian Explosion?

The sudden appearance of highly developed and diversified animals in Cambrian rock. Almost all known phyla (body plans) are found in the Cambrian.

Define one half life of potassium (40K)

The time it takes for 1/2 of 40K to decay to 40Ar to 40Ca.

If Noah's flood were to happen today, what would happen to different biomes as the floodwaters rose?

There would be a succession of biomes encountered and buried in a predictable order as the floodwaters rose.

If the assumptions of radiometric dating are correct, how much time did it take the deposit the Phanerozoic fossil record?

Well over 500 million years.

What is adaptive radiation?

When a single or small group of ancestral species rapidly diversifies into a large number of descendant species that occupy a wide variety of ecological niches.

What is stasis?

When new species appear and then persist for long periods of time without apparent change.

How does 14C get incorporated into plants?

When plants take in CO2 and use it to synthesize new molecules and plant tissue they incorporate both 14C and 12C.

List 4 factors that cause different environmental conditions, such as different temperatures and humidity, to be found in different biomes.

altitude, latitude, climate, local geography