68 terms

Unit 6 Test Review - Geologic History


Terms in this set (...)

What is fossil?
Remains of an ancient organism or its activity
What kinds of rocks are fossils found in?
Sedimentary rocks
What are the best locations for organisms to die so a fossil might be recorded?
Best locations - bottom of lake or ocean or in a layer of volcanic ash.
What help determine the absolute and relative ages of rocks?
What provides clues to past geologic events, climates, and evolution of living things?
What are an indicator of an area's ancient environmental conditions and climates?
Why do fossils not form in igneous rocks?
Igneous rocks are too hot.
Why do fossils not form in metamorphic rocks?
Metamorphic rocks require too much heat and pressure to have fossils.
What is Absolute Age?
Absolute Age is a numeric dating that is based on Radiometric dating using radioactive isotopes; tells how many millions of years old something is.
Why are radioactive substances useful for measuring geologic time?
Radioactive substances undergo radioactive decay at predictable rates.
What is Relative (Age) Dating?
Relative dating tells which layers of rock or fossils are older or younger without specific dates; is based on oldest layers are below newer layers.
How does the mineralization of fossils occur?
1. Mineralized water fills the pores of the organic tissues and moves through the cellular spaces.
2. Water evaporates.
3. Excess minerals replace tissues over time.
Name some kinds of Trace Fossils.
Trace fossils include Tracks, Trails, Footprints, Burrows, and Borings
True or False: Most multicellular life appeared less than 500 million years ago.
TRUE! Most multicellular life appeared less than 500 million years ago.
What are the best indicators of an area's ancient conditions and climate?
TYPE and DISTRIBUTION of FOSSILS are the BEST indicators of an area's ancient conditions and climate.
What is the Law of Superposition?
In an undisturbed rock column, the oldest rocks will be on the bottom and the youngest ones on top.
True or False: Fossils provide important geologic information by revealing only the absolute age of rocks.
FALSE! Fossils provide important geologic information by revealing BOTH the absolute and relative ages of rocks.
What are the beginnings and endings of Geologic eras defined by?
Beginnings and ends of Geologic eras are defined by major changes in life forms based on fossil evidence.
Would we expect to find similar or different fossils grouped in rocks from the same time period in history?
Rocks grouped within each time period contain SIMILAR fossils.
Name the three eras in the Phanerozoic eon from oldest to youngest.
Paleozoic, Mesozoic, Cenozoic
Why is the Cenozoic era divided into Epochs but the Mesozoic and Paleozoic eras are not?
Because the Cenozoic covers the last 65.5 million years, we know the most about it.
Name some characteristic of the Precambrian Era.
Earth was forming and cooling, heavy bombardment of planet by asteroids, continents were forming, first life - single celled organisms, first ocean, some small multi-cellular organisms
Name some characteristic of the Paleozoic era.
Age of fishes, first marine life, first fishes, first amphibians, first land plants, first reptiles, first forests.
Name some characteristic of the Mesozoic era.
Age of Reptiles, dinosaurs rise and fall, first birds, first small mammals, first flowering plants
Name some characteristic of the Cenozoic era.
Age of Mammals, first placental mammals, first large mammals, first humans
Name the periods of the Paleozoic era, oldest to youngest.
Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Mississippian and Pennsylvanian), and Permian
Name the periods of the Mesozoic era, oldest to youngest.
Triassic, Jurassic, Cretaceous
Name the periods of the Cenozoic era, oldest to youngest.
Tertiary, Quaternary
When was the first mass extinction?
First Mass Extinction was in the Ordovician Period.
When was the second mass extinction?
Second Mass Extinction was in the Devonian Period.
When was the third mass extinction?
Third Mass Extinction was at end of the Permian Period.
When was the fourth mass extinction?
Fourth Mass Extinction Event was at end of the Triassic period.
When was the fifth mass extinction?
Fifth Mass Extinction Event was at end of the Cretaceous period.
During which period were Pangaea and Appalachian Mountains formed?
They formed during the Permian period.
During which period did the dinosaurs dominate?
Dinosaurs dominant life form during Jurassic.
Using the chart at the END of your Index Fossil notes (#4), answer this: You have rock that you know dates from the Ordovician period. Name one fossil you would expect to find in it?
Bathyurus OR Tetragraptus
What is an Index Fossil?
a fossil that scientists use to date rocks; they are found widely scattered in rocks over a large region existed for a short geologic time.
True or False? A fossil must be ABUNDANT, UNCOMMON, DISTINCTIVE, and LIMITED in order to be considered an index fossil.
FALSE! An index fossil must be:
Abundant - distributed over a wide area.
Common - large numbers within a rock layer.
Distinctive - easy to recognize.
Limited - from a short, specific geologic time span.
Can an index fossil be used to date sedimentary rocks in two different places on Earth?
Index fossils can be used to date rock layers found in widely separated areas. They also can help determine the age of sedimentary rock.
What is the most diverse group of extinct animals preserved in the fossil record?
Name some Index Fossils that we learned.
Trilobite, Ammonite, and others listed in the chart
What can fossils tell us about the age of the rocks they are found in?
If it is an Index Fossil, it can tell us the absolute age of the rock it is in and the relative ages of the rocks above and below it.
What can fossils tell us about their environment?
Marine (Ocean): If the fossil is similar to a current ocean organism, it probably lived in the ocean. Thick shelled organisms lived in shallow water and thin-shelled organisms lived in deep water.
Land (Terrestrial): If the fossil is a plant and has rings or pollen, it can tell us about the climate. We can also do leaf analysis to determine the temperature.
Fossils of ocean/marine organisms have been found in the Rocky Mountains. How is this explained in Earth Science?
The Rocky Mountains were not always mountains and were once much lower and the land was part of an ocean.
What is a way to tell the temperature of a past climate using leaves?
A way of telling average temperature by looking at the shape of leaves is LEAF MARGIN ANALYSIS.
Warm tropical areas have a higher PERCENT of plants with smooth edges.
Cooler environments have a higher PERCENT of plants with leaves with more toothed edges.
Using the Leaf Analysis graph in your Fossils: Past Environments notes (#4), determine the following: If 25% of all fossil leaves found in an area are smooth and 75% are toothed, the past climate was most likely about what temperature?
8 degrees Celsius
What is a Mass Extinction Event?
A catastrophe for the world's living organisms, a rapid event (shorter than 10,000 to 100,000 years), and a significant part of all life on Earth became extinct.
Which mass extinction event was the biggest, when was it, and what is the percentage of organisms that died?
The THIRD mass extinction event - the "Great Dying" - was at the end of the Permian Period (end of the Paleozoic Era). Almost 96% of all organisms were killed
What are the two theories concerning the cause of the fifth mass extinction event - the event that killed the dinosaurs?
The METEORITE theory (meteorite hit near Mexico) and the VOLCANO theory (increased volcanic activity on Earth).
Using the diagram on Review #6, be able to label all five of the Mass Extinction Events.
What are some possible causes of mass extinction events?
Meteorite Impact, Volcanoes, Climate Change, Changes in Atmosphere, Variations in Solar output, Changes in sea level, Changes in Orbit, Changes in Magnetic Field, Changes in solar orbit on galactic plane, Nearby Gamma Ray bursts
Most probably combination of events....
What happens to the biodiversity of life after a mass extinction event?
Surviving species take over vacant habitats and resources.
New species develop and fill in vacant habitats. As a result biodiversity increases.
When was the SIXTH extinction and what is considered the cause?
The SIXTH Mass Extinction Event is going on now and Humans and their activities are the cause.
TRUE or FALSE? The fossil record shows us that fossil species can disappear and then reappear many years later.
FALSE! Fossil species appear and disappear throughout time but they cannot disappear and reappear many years later.
What is the Principle of Fossil Succession?
The Principle of Fossil Succession tells us that different species of fossil organisms appear in a definite order.
Oldest organisms are at the bottom - newest at the top.
Once a fossil species disappears in a sequence of strata, it never reappears higher in the sequence.
TRUE or FALSE? Most fossils are the remains of extinct organisms.
TRUE! Most fossils are the remains of extinct organisms; they belong to species that are no longer living anywhere on Earth.
What causes the change in organisms over time?
Changes in Earth's environment over time results in changes in organisms.
TRUE or FALSE? Fossil evidence shows life becomes less complex over time.
FALSE! Fossil evidence shows life becomes MORE complex over time.
Who first proposed Natural Selection?
Charles Darwin
What is Natural Selection?
Natural Selection describes the process by which organisms that are best suited to the environment are most likely to live and pass on their genes (traits). It is a Gradual process. Organisms with less suitable traits fail to survive and/or pass on their genes.
TRUE or FALSE? Life responds to environmental changes.
TRUE! Environmental change is any change in an environment to which an organism must adapt.
Can be gradual, ex: mountains form and can be quick, ex: floods volcanoes.
Environmental change forces the organism to adapt.
Clues to changes in organisms over time be found in ____________________ anatomy.
Clues to changes in organisms over time can be found in STRUCTURAL anatomy.
What does HOMOLOGOUS mean? Give an example.
Homologous describes anatomical structures that have SIMILAR STRUCTURE but often have different functions. The organisms with homologous structures have COMMON ancestor but have diverged over time. An example would be the arm and hand of a human and a cat.
What does ANALOGOUS mean? Give an example.
Analogous describes anatomical structures that have SIMILAR FUNCTIONs but have different structures. They are different solutions to same problem and evolved independently. The organisms are NOT RELATED - they are not from common descent. An example would be the wing of a butterfly and the wing of a bird.
What does VESTIGIAL mean? Give an example.
Vestigial describes anatomical structures that serve no apparent purpose in the organism where they are found. However, they may serve a function in a related species and likely served purpose in ancestors. They also provide clues to ancestry. An example is the pelvic bones in whales. Pelvic bones are used for walking.
TRUE or FALSE? Fossilization is common.
FALSE! Fossilization is rare - most organisms are extinct.
What does the fossil record show us about the development of organisms over time?
The fossil record shows a succession of incremental development from one species to another.
Where does most of the evidence for evolution come from?
The Fossil Record: Much of the evidence for the evolution of life-forms on Earth has been obtained by examining fossils preserved in rock layers.

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