Ch 8 Fossils
Terms in this set (81)
Which of the following are correct statements about fossils?
-Fossils are the remains of once-living organisms, wholly or partially transformed into rock. The most common types of mammal fossils are bones and teeth
-Fossils provide an essential historical record for documenting and understanding the biological evolution of surviving and non-surviving lineages
-Fossils provide information on chronology and geologic time
-Fossils and their geologic settings reveal information about past diets and environments
You have discovered a fossil-bearing layer in East Africa and you wish to estimate its age. There are abundant fossils of many savanna species, and you have identified most of them to species or genus. You know that the genus Equus makes its first appearance in Africa at 2.3 mya, and the species Connochaetes gnou first appears at about 1.07 mya.
1) If your site includes Equus but not Connochaetes gnou,: it may date back to between 1.07 and 2.3 mya
2) If your site includes both Equus and Connochaetes gnou,: it is probably younger than 1.07 mya
3) If your site contains neither Equus nor Connochaetes gnou,: you cannot determine the relative date of this site using these species
Which statements about the fossil and living records of species are correct?
-The combined record of living species and fossil species is essential for understanding evolution
-Living species provide an incomplete picture of evolution because only surviving lineages are represented
Iron-containing particles in sediment or molten rock will orient with the Earth's magnetic field as it settles or cools
An element decays radioactively at a known rate expressed as the half-life
Electron Spin Resonance Dating
Buried fossils absorb radioactive isotopes from the surrounding burial environment
Stable Isotope Analysis
Variants of nonradioactive elements with slightly different masses are incorporated into living organisms in different amounts depending on environmental conditions
Analyzes radioactive isotopes and provides exact date ranges
Compares fossils and objects to each other and does not provide exact dates
Does not use isotopes but does provide exact dates
What was Pangaea?
The supercontinent that existed around 200 million years ago. All current continents are derived from this land mass
Which are correct statements about radiocarbon dating?
-The parent/daughter elements are 14C to 14N
-14C can occur in any organic material
-Radiocarbon dating is possible because a living organism stops incorporating new 14C into its body when it dies
Does every part of an organism have the same chance of becoming fossilized?
No. Hard parts of the body preserve better because they have biologically deposited minerals. Soft tissues only rarely preserve because they are made of polymers that bacteria eat.
Who founded the Principle of Faunal Succession?
Who was one of the first paleontologists to scientifically describe many ancient species?
Who discovered an extinct ground sloth in Virginia?
President Thomas Jefferson
the study of what happens to an organism's remains after death
What is the single most important variable that we can measure to understand past changes in climate?
Which occurred as ancient climate changed?
-One of the most profound temperature changes, and thus dramatic alterations of climate and habitat, began at the end of the Miocene, around 6 mya
-During very warm periods, sea levels are very high
-Since the Eocene, there has been a general cooling of the Earth's surface temperature
Some of the best information on climate history- and especially temperature- is based on the study of ________.
Begin with the material that is most likely to fossilize, and finish with the material least likely to fossilize.
-bones of an adult mammal quickly buried
-bones of an adult mammal left on the surface
-soft body parts of any animal
Fission Track Dating
uranium, green picture
Global Temperature Reconstruction
phylogenies inherently produce a time scale
Why is the Fayum Depression important?
-Other African fossil deposits that date to the same period as the Fayum Depression are very rare or fossil free
-The geological record at the Fayum Depression, Egypt, includes fossils dating from around 37 to 29 million years ago
_______ dating is a form of absolute dating in which the sample is bombarded with fast neutrons in a nuclear reactor to measure the ratio of argon 40 to argonm 39 in a sample. This method only works on _____ rocks.
The study of the deposition of organic remains and the environmental conditions affecting their preservation
Place the following absolute dating methods in order, beginning with the method that can analyze the oldest materials and ending with the method that can analyze the youngest:
-fission track dating
paleomagnetic dating, fission track dating, thermoluminescence dating, dendrochronology
This image (8.33) shows the Serengeti Plain in Kenya, where like across much of the African continent, ___________ have given way to a greater abundance of _______ as forests have changed to woodlands or open savannas.
What is true about the relationship between fossils and their environment?
-Correct placement of fossils in the environment where their living counterparts thrive helps us understand the factors that shaped that organism's evolution
-Correct placement of fossils in time helps in documenting evolutionary relationships among species (phylogeny)
Through the careful study of _____, the paleontologist Charles Brain realized that the early hominin bones found in South African caves as well as the bones of many other kinds of animals often got into the caves because of ___________.
bone accumulations, carnivore activity
Which of the following objects can be used for relative dating and which can be used for absolute dating?:
-wood from trees
-metal grains from sediments
Relative: pig molars, Oldowan chopper
Absolute: wood from trees, metal grains from sediments
Match each dating method to the physical principle that allows it to work:
-parent daughter decay: Radiopotassium Dating
-decay of L isomers into D isomers: Amino Acid Racemization
-energy from the Sun lost when materials were heated long ago: Thermoluminescence Dating
-traces from decay of Uranium 238: Fission Track Dating
Radiopotassium dating is used for establishing chronologies of ancient hominin sites. Which of the following statements are true of radiopotassium dating?
-first applied to date the oldest stratum at Olduvai Gorge to about 1.8 mya
-can be used to date fossils up to 1.3 billion years old
Which conditions are likely to help preserve animal reserves, making it more likely for them to become fossils?
rapid burial, low levels of oxygen in the sediment in which remains are buried
You have a sample of bone found on an archaeological site and you want to estimate its age. Which of the following methods would you try?
Radiocarbon using the 14C to 14N parent daughter decay system
Which statements about the methods and principles used by scientists to study the past are correct?
-Geologic time provides the grand scale of the evolution of life
-Past climates can be reconstructed via the stable isotopes of oxygen
-Ancient animals' diets and their habitats can be reconstructed through the stable isotopes of carbon
Which statements are true regarding the use of stable oxygen isotopes in reconstructing ancient climates?
-Oxygen is incorporated into biological tissues of living organisms
-Oceanic microorganisms preserved in sea floor sediments or elsewhere can be analyzed to measure the ratio of oxygen16 to oxygen18
-As global temperature varies, the amount of oxygen18 water changes in response
In the year ____, James Ussher added up all the generations of religious patriarchs listed in the text of _________, and reported that Earth was created around _____.
1654, the Old Testament, 4004 BC
Bones slowly absorb flourine from the surrounding soil at a regular rate (locally)
Index species are species that appear in or disappear from a given region at known dates
Steno's law of superposition
Geological processes can lay down stratigraphy over time
Match each of these pairs of parent daughter isotopes used in radiometric dating to its half life
40K -> 39Ar: 1.3 billion years
14C -> 14N: 5,730 years
235U -> 207 Pb: 713 million years
Good representation of fossils is important in understanding evolution. Which of the following statements about representation are correct?
-There are hundreds of fossils representing primates and other animals from around 55 mya
-Fossils are not uniformly preserved for all time periods and regions. Rock sequences containing fossils are not always complete
-It is assumed that many fossil-bearing deposits exist but have not yet been discovered or investigated
How did Charles Darwin incorporate fossils into his work?
-Based on fossil analysis, Charles Darwin recognized the similarity between extinct ground sloths and closely related, living sloths
-Charles Darwin knew about fossils and discovered several in Argentina
All of the following are ABSOLUTE methods of dating EXCEPT:
-amino acid dating
-tree ring dating
-fission track dating
Rapid evolutionary change during long, static periods is known as:
Your professor is planning to undertake chemical isotope analysis for her latest paleoanthropology project. When you ask her for more details, she invites you to guess the topic of her project based on this fact alone. You suggest that her project may be about:
a) figuring out the age of a fossil hominin
b) determining the kinds of food a hominin ate
c) understanding what type of habitat a hominin lived in
d) any of the above are correct
d) any of the above are correct
The study of what happens to an organism's remains after death is:
Studies of temperatures during the Cenozoic era suggest that:
temperatures have fluctuated, sometimes greatly, over time
Igneous (volcanic) rock can be dated with which of the following methods?
Paleosols and fauna in the Middle Awash Valley of Ethiopia show that:
the earliest hominins lived in wooded settings
Which of the following is NOT an ideal environment for fossilization?
-acidic soil (as in a jungle)
A hearth is discovered with bone fragments in it. What method might be used to date the bone?
amino acid method
The time it takes for 50% of an unstable isotope to decay to a stable form is called the:
The molecular clock has been useful to determine the phylogenetic relationships of species based on the assumption that:
a species accumulates genetic differences over time at a constant rate
Most of the fossils discovered in Africa come from the eastern and western parts of the continent. Why is this?
These areas provided better preservation
Which of the following statements is INCORRECT?
-Dating methods may be relative or absolute (numerical)
-Radioactive decay is central to some of the basic methods of determining absolute dates
-Past climates can be reconstructed using isotopes of oxygen
-Ancient diets and habitats can be reconstructed using isotopes of carbon
-All of these are correct
-All of these are correct
Provide a record that documents biological evolution of surviving and non-surviving lineages of organisms
Which of the following elements can be used in radiometric dating?
a. uranium (U)
b. potassium (K)
c. argon (Ar)
d. All of the above are correct.
d) all of the above are correct
You want to undertake a project to study the past environment in which the Inuit lived in Greenland. Your professor suggests that you think about climate, specifically that you:
test microorganisms in the ocean to estimate temperature fluctuations
The molecular clock indicates that humans and chimpanzees diverged about ___ mya
According to Bushop Ussher, when was Earth created?
6,000 years ago
A volcanic eruption on the coast of Japan in 1850 deposits a layer of ash on top of a layer of red clay, and the ash is covered by a layer of silt in a tsunami in 1902. Archaeologists find a coin between the ash and silt, and they find a small pot between the ash and clay. Given this sequence of events, which of the following is true?
The pot is older than the coin
Scientists can determine the type of plant consumed based on:
carbon 13 and carbon 12
What is the basic difference between relative and absolute dating?
the use of an actual number of years
Based on the molecular clock, geneticists believe the split between chimps and hominins occured:
Chemical analysis of the ______ can provide information on diets and habitats
bones and teeth
The era in which we are living is the:
To calculate the numerical age of a fossil specimen that you believe dates to about 2 mya, which of the following methods would you choose?
A team of paleoanthropologists has concluded based on skeletal anatomy that the new species they found, Oreopithecus, lived in an arboreal habitat. This conclusion may have been based largely on the apes'
long arm bones
For fossilization to occur, bones should meet the following taphonomic requirements:
the bones must remain in an anoxic environment
The objects seen here can be used (picture of tree rings):
-to date recent archaeological sites in the southwest United States.
-as a way to radiometrically age an archaeological site using its carbon content.
-as a method for numerically dating another object or event.
-All of the above are correct.
All of the following are relative methods of dating EXCEPT:
5,730 years is the ______________ of the carbon-14 radioisotope
Stratigraphic correlation is:
matching strata by chemical composition and color from several sites across distances.
To reconstruct and interpret evolutionary changes, it is crucial to place each fossil in time. This is called:
a chronological sequence
Thermoluminescence dating can provide dates when used on which types of materials?
sediment, stone, and ceramics
The study of fossils is called: