Chapter 7 Flashcards
Ichthyosaurus
fish lizard
What were some of Mary Anning’s discoveries?
She excavated a complete fossilized skeleton of an ichthyosaurus (fish lizard), Pterodactylus macronyx (flying creature), and a Plesiosaurus (fish creature)
Why were Annings discoveries and contributions not recognized as much as they should have been?
Because the Geological Society of London was closed to women
Extinct
terminated or vanished
Extant
still surviving
Deep Time
Scotsman James Hutton’s theory gave the history of Earth enough time—4.543 billion years—to encompass continental drift, the
evolution of species, and the fossilization process
Uniformitarianism
Charles Lyell’s theory claimed the
doctrine that Earth’s geologic formations are the work of slow geologic forces
Catastrophism
the belief that Earth’s formation was due to a set of relatively
quick biblical catastrophic events
Fossils
the mineralized copies of once-living organisms
Why was there such resistance to the idea that animals and people may have evolved over time?
To even consider that humans and animals might have evolved over time was practically an admission that the Christian God had made mistakes that needed correction in His creation of Earth and all living things. To think otherwise was considered heresy and was punishable by ex-communication from the Church—or even death. Instead, scientists were still trying to fit geologic evidence into Biblical chronology
Why is the study of fossils important in anthropology?
because these answers provide insights into human evolution
Eon
The largest subunit of geologic time
Era
An eon is further divided into eras
Period
eras are divided into periods
Epoch
periods are divided into epochs
Holocene
the current epoch
Anthropocene
This has led some scientists within the stratigraphic community to argue for a new epoch beginning around 1950 with the Nuclear Age called the Anthropocene. The major event that marks the boundary is the warming temperatures and mass extinction of nonhuman species caused by human activity
What are some arbitrary ways scientists might determine where one unit of time begins and another ends?
Events like
significant shifts in
climate or mass extinctions can be used to mark the end of one geologic time unit and the beginning of another
Summarize the current debate about the epoch we are currently in. Include human activity in your answer.
Some say it is simply a warm blip in a larger epoch that includes the Pleistocene and not a new epoch called the Holocene. Others say human-driven climate change is warming the world and changing environmental patterns faster than the natural cyclical processes, which means a new epoch from the industrial revolution called the Anthropocene should be formed.
Abraham Ortelius
Ortelius came up with the concept that one supercontinent called Pangea had existed much earlier in Earth’s history
Pangea
One supercontinent called Pangea existed much earlier in Earth’s history. Approximately 200 million years ago, Pangea started to slowly break apart, with the resulting pieces of land shifting and moving through the process of continental drift.
Continental Drift
Pangea started to slowly break apart, with the resulting pieces of land shifting and moving through the process of continental drift
Laurasia
one of the two supercontinents
Gondwanaland
one of the two supercontinents
Alfred Wegener
There was a debate where there was suspicion that there wasn’t enough time for landmasses to move. However, he found fern fossils on every continent, which made him realize all of the continents had to have been connected at one point, which led him to create the tectonic plate theory.
Glossopteris
the name of the fossilized remains of a fern that Alfred Wegner found
Tectonic Plate Theory
Earth’s landmasses are relatively thin, brittle fragments floating on top of hot, squishy material. There is bound to be movement, even of large fragments. Furthermore, there are ridges or shelves in the Atlantic and Pacific Oceans that reflect the shifting of the planet’s crust. This theory not only supports the breakup of Pangea but also provides the basis for our current understanding of how earthquakes work.
What does the Red Panda tell us about a “supercontinent?”
Red Panda fossils have been found four million years to the late Miocene era. They are considered living fossils because they have changed so little in millions of years and because they are represented in the fossil record. Thus, the existence of the red panda in the Miocene in the Appalachian Mountains but living only in Asia today is clear evidence that the red panda moved freely and that our continents were part of a supercontinent.
Taphonomy
the study of what happens to an organism after death
Why is taphonomy important in biological anthropology?
To obtain as much information as possible from the remains of once-living creatures, one must understand the processes that occur after death. It is so important that many scientists have recreated a variety of burial and decay experiments to track taphonomic change in modern contexts. These contexts can then be used to understand the taphonomic patterns seen in the fossil record
What have anthropologists learned from Suddern Farm?
Since there is no universal or “normative” burial rite, taphonomic study is crucial to figuring out what cultural and ritual processes were operating at this time. P78 may represent a special ritual burial associated with violence or punishment. By better understanding the processes that occur in and to the body after death, we can reconstruct the cultural, biological, and geologic processes that affect remains.
What might taphonomic analysis reveal about human culture, or the challenges people faced?
Taphonomic analysis can also give us important insights into the development of complex thought and rituals in human evolution. Taphonomy helped to establish whether these burials were simply the result of natural processes or intentionally constructed by humans. Taphonomic evidence may tell us how our ancestors died.
Bog Bodies
a dead body that is preserved through peats/soil from wetlands
Anaerobic
absence of oxygen
Ice mummy
a specimen of human remains that is naturally mummified by extreme low temperatures.
What are special circumstances in which bodies can be preserved for many years?
The most important element in the preservation of remains is a stable environment
What role does oxygen play in the body’s decay?
Much of the bacteria that causes decay is already present in our gut and can begin the decomposition process shortly after death during putrefaction. Since oxygen is necessary for the body’s bacteria to break down organic material, the decay process is significantly slowed or halted in anaerobic conditions
Fossilization
the preservation of an organism against these natural decay processes
Lithification
the weight and pressure of the sediments squeeze out extra fluids and replace the voids, that appear in the remains as they decay, with minerals from the surrounding sediments. Lithification is how soft sediments, the end product of erosion, become rigid rock
Premineralization
This is when the organism is fully replaced by minerals from the sediments
Why don’t most creatures end up fossilized after death?
There are many stages in fossilization and if the process is disturbed at any of the stages, the organism will fail to become a fossil. After all, organisms are set up to deteriorate after we die. Bacteria, insects, scavengers, weather, and the environment all aid in the process that breaks down organisms so their nutrients, molecules, and elements can be returned to Earth to maintain ecosystems.
Petrified wood
Another type of fossilized plant. This fossil is created when actual pieces of wood—such as the trunk of a tree—mineralize and turn into rock. Petrified wood is a combination of silica, calcite, and quartz, and it is both heavy and brittle. Petrified wood can be colorful and is generally aesthetically pleasing because all the features of the original tree’s composition are illuminated through mineralization.
How does wood become petrified?
It forms when plant material is buried by sediment and protected from decay due to oxygen and organisms.
Hominins
includes all human ancestors who existed after the evolutionary split from chimpanzees and bonobos
Homo Sapiens
Modern humans are Homo sapiens
Australopithicus Afarensis
is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa
“Lucy”
A hominin that is 3.2 million-year-old fossil of Australopithecus afarensis that was discovered in Ethiopia in 1974. Originally thought to be the most complete until the discovery of little foot.
“Little Foot”
Little Foot is more complete than Lucy and possibly the oldest fossil that has so far been found, dating to at least 3.6 million years
Sahelanthropus tchadensis
The oldest hominin fossil is a fragmentary skull named Sahelanthropus tchadensis, found in Northern Chad and dating to circa seven mya
Amber
fossilized sap of coniferous trees
How does amber preserve insects or other forms of life?
Sometimes pieces of amber contain inclusions such as air bubbles or insects that become trapped in the sap
What actual discovery might provide insight into ancient DNA?
the recent discovery of a tick that fed off of dinosaur blood that is trapped in amber
La Brea Tar Pits
A famous fossil site from California has asphalt that bubbles through the cracks in sidewalks
Pleistocene
ice age era
Megafauna
Large animals such as mammoths and mastodons
Canis dirus
dire wolves
Smilodan fatalis
saber-toothed cat
Describe how asphalt preserves animal and plant remains.
perished animals are entrapped in the asphalt
What has the Los Angeles basin taught scientists about life thousands of years ago?
The La Brea Tar Pits Museum provides an incredible look at the both extinct and extant animals that lived in the Los Angeles Basin 40,000–11,000 years ago
Rhinocerotid skull
rhino skull. Part of a giant rhinocerotid skull dating back 9.2 mya to the Miocene was discovered in Cappadocia, Turkey, in 2010.
Miocene
kelp first formed
Why are so few fossils found in igneous rock?`
It is rare for fossils to survive molten lava, and it is estimated that only 2% of all fossils have been found in igneous rock
Explain why the skull found in Turkey is an exception to this rule.
The rhino fossil was a remarkable find because the eruption of the Çardak caldera was so sudden that it simply dehydrated and “baked” the animal
Trace Fossils
evidence of biological activity such as footprints, nests, burrows, tooth marks, shells
Laetoli footprints
These 70 footprints, now referred to as the Laetoli Footprints, were created when early humans walked in wet volcanic ash in Tanzania
Pech Merle Cave
At Pech Merle cave in the Dordogne region of France, archaeologists discovered two fossilized footprints. The approach worked as many other footprints belonging to as many as five individuals were discovered with the expert eyes of the trackers
Bezoars
hard, concrete-like substances in the intestines of fossilized creatures
Coprolite
fossilized dung
In matrix
like all fossilized materials, can be in matrix—meaning that the fossil is embedded in secondary rock
Phytoliths
65 million-year-old grass phytoliths microscopic silica in plants) found in dinosaur coprolite in India revealed that grasses had been in existence much earlier than scientists initially believed
Give examples of trace fossils found around the world.
Tanzania and France.
What can anthropologists learn from bezoars and coprolite?
anthropologists can glean a great deal of information from bezoars (intestines) and coprolite (dung) about the diets of ancient animals and the environment in which the food sources existed.
Pseudofossils
pseudofossils are not misrepresentations but rather misinterpretations of rocks that look like true fossilized remains. Pseudofossils are the result of impressions or markings on rock, or even the way other inorganic materials react with the rock. A common example is dendrites, the crystallized deposits of black minerals that resemble plant growth
Mary Leakey
British anthropologist who discovered fossilized animal tracks at Laetoli
Laetoli
Animal tracks and footprints
What special circumstances allowed the Laetoli footprints to be preserved?
Before the impressions were obscured, more volcanic ash and rain fell, sealing the footprints
What did anthropologists learn about the hominins who made the tracks?
The footprints were made 3.6 mya. The footprints clearly indicate a bipedal hominin who had a foot similar to that of modern humans with short legs.
Describe what is meant by “context.”
Objects and fossils are interesting in and of themselves, but without context there is only so much we can learn from them. One of the most important contextual pieces is the dating of an object or fossil. When it was made. By being able to place it in time, we can compare it more accurately with other contemporary fossils and artifacts or we can better analyze the evolution of a fossil species or artifacts.
Relative Dating
they rely on simple observational skills. Christian Jürgensen Thomsen categorized the artifacts at the museum based on the idea that simpler tools and materials were most likely older than more complex tools and materials
Christian Jurgensen Thomsen
Came up with the relative dating theory
Stratigraphy
A relative dating method that is based on ordered layers or strata) that build up over time. Essentially, superposition tells us that things on the bottom are older than things on the top
Nicholas Steno
first proposed the Law of Superposition
James Hutton
further explored the Law of Superposition by Nicholas Steno
Law of Superposition
Essentially, superposition tells us that things on the bottom are older than things on the top. It stands to reason that each layer is older than the one immediately on top of it
Biostratigraphy
This form of dating looks at the context of a fossil or artifact and compares it to the other fossils and biological remains plant and animal) found in the same stratigraphic layers
Cultural Dating
This relative dating technique is used to identify the chronological relationships between human-made artifacts. For instance, a pocket knife by itself is difficult to date. However, if the same pocket knife is discovered surrounded by cassette tapes and VHS tapes, it is logical to assume that the artifact came from the 1980s or 1990s like the cassette and VHS tapes.
Fluorine Dating
Chemical dating was developed in the 19th century and represents one of the early attempts to use soil composition and chemistry to date artifacts. Fluorine Dating is a chemical type of dating. It is commonly used to compare the age of the soil around artifacts located in close proximity.
Describe the “three age” system and its disadvantages.
The restriction of relative dating is that you don’t know specific dates or how much time passed between different sites or artifacts. You simply know that one artifact or fossil is older than another.
How does cultural dating work? What does an anthropologist already need to know in order to effectively use cultural dating?
Both cultural dating and biostratigraphy are most effective when you are already familiar with the time periods for the artifacts and animals
What is fluorine dating? Why can it be difficult to use? In what situations is it particularly useful?
Unfortunately, this absorption rate is highly sensitive to temperature, soil pH, and varying fluorine levels in local soil and groundwater. This makes it difficult to get an accurate date for the remains or to compare remains between two sites. However, this technique is particularly useful for determining whether different artifacts come from the same burial context
How was fluorine dating used to determine that “Piltdown Man” was a forgery?
Fluorine analysis determined that the jaw and cranium in piltdown man had different fluorine signatures. Thus, these bones could not have come from the same individual in the same burial environment
Chronometric Dating
provides specific dates and time ranges. Many of the chronometric dating methods are based on the measurement of radioactive decay of particular elements.
Elements
are materials that cannot be broken down into more simple materials without losing their chemical identity
Atom
Each element consists of an atom that has a specific number of protons positively charged particles) and electrons negatively charged particles) as well as varying numbers of neutrons particles with no charge)
Isotopes
Atoms of a given element that have different numbers of neutrons are known as isotopes
Stable Isotopes
Most isotopes in nature are considered stable isotopes and will remain in their normal structure indefinitely.
Unstable Isotopes
However, some isotopes are considered unstable isotopes sometimes called radioisotopes) because they spontaneously release energy and particles, transforming into stable isotopes
Radioactive Decay
The process of transforming the atom by spontaneously releasing energy is called radioactive decay.
Radiocarbon Dating
The leading chronometric method for archaeology is radiocarbon dating. This change occurs at a predictable rate for nearly all radioisotopes of elements, allowing scientists to use unstable isotopes to measure time passage from a few hundred to a few billion years with a large degree of accuracy and precision.
Potassium-argon (K-Ar) Dating
can reach further back into the past than radiocarbon dating. Used to date volcanic rock, these techniques are based on the decay of unstable potassium into argon gas, which gets trapped in the crystalline structures of volcanic material.
Fission Track Dating
is another useful dating technique for sites that are millions of years old. This is based on the decay of radioactive uranium. The unstable atom of uranium fissions at a predictable rate. The fission takes a lot of energy and causes damage to the surrounding rock.
Luninescence Dating
which includes thermoluminescence and a related technique called optically stimulated luminescence, is based on the naturally occurring background radiation in soils. Pottery, baked clay, and sediments that include quartz and feldspar are bombarded by radiation from the soils surrounding it. When heated to 500°C thermoluminescence) or exposed to particular light wavelengths optically stimulated luminescence) in the laboratory, this energy gets released in the form of light and heat and can be measured
Electron Spin Resonance Dating
is based on the measurement of accumulated background radiation from the burial environment. It is used on artifacts and rocks with crystalline structures, including tooth enamel, shell, and rock—those for which thermoluminescence would not work
Dendrochonology
It is based on the natural growth patterns of trees. As most of you probably learned in elementary school, trees create concentric rings as they grow. The width of those rings depends on environmental conditions and season. In a perfect world, you can tell the age of a tree by counting the rings.
Amino acid racemization
is a dating method that is used for organic materials such as bones, teeth, and shell. Organic tissues include amino acids that help build their structure
How is chronometric dating different from relative dating?
Based on radiation
Why do unstable isotopes give scientists clues about the age of an artifact or a fossil? In your answer, use as many words from the center column as possible).
How does radiocarbon dating work? What are some of its limitations?
How does K-Ar and Ar-Ar dating work? What advantage do these methods have over radiocarbon dating?
How does Fission Track dating work? When would scientists use this method?
How does luminescence dating work? When would anthropologists use it?
How does Electron spin resonance dating work? When would scientists use it?
What information can dendrochronology provide to scientists? What are some challenges in using it?
Paleomagnetic/ Geomagnetic reversals
the poles are actually magnetic fields, and geomagnetic poles are not located in the same places as geographic poles. Just to complicate the matter, magnetic poles move around
How does amino acid racemization work? What dating method is it similar to?
Describe paleomagnetic/geomagnetic reversals. How can they help scientists determine the age of rocks?
What implications for the future might these reversals have?
Sediment cores
Core samples taken from lake beds or other water sources for analysis of their pollen
What can the environment tell us about the creatures who lived in it?
Another important part of understanding human evolution and evolution in general) is understanding the way in which an organism’s environment affects its survival.
What information can sediment cores give us?
By taking a core sample and analyzing the pollen and other organic material, an archaeologist can build a timeline of plant types and see changes in the vegetation of the area.
How do stable isotopes help scientists identify what kind of an environment an animal or a plant lived in?
Stable isotopes can be powerful tools for identifying where an organism grew up and what kind of food the organism ate throughout its life. They can even be used to identify global temperature fluctuations
Glacial periods
Periods characterized by low global temperatures and the expansion of ice sheets on Earth’s surface.
Foraminifera
The microorganisms that live in the oceans absorb the water from their environment and use the oxygen isotopes in their body structures
What can 16O and 18O tell us about ocean temperature?
Cooler temperatures indicate higher ratios of 18O.
How can microorganisms that lived and died in oceans help us understand water temperature of the past?
Scientists can extract these ocean cores and sample the remains of foraminifera for their 18O and 16O ratios. These ratios will give a good approximation of global temperatures deep into the past.
Explain how analyzing the carbon in bones and teeth can help scientists determine what kind of plants an animal or person ate.
By analyzing the stable isotopes in the bones and teeth of humans and other animals, we can identify the types of food they ate at different stages of their lives as well as where they lived
How can scientists determine if a person’s diet was primarily vegetarian or meat-based?
An animal who has a mostly vegetarian diet will have lower ratios of 15N to 14N, those further up the food chain, like carnivores, will have higher ratios of 15N.
How else can scientists use ratios of 15N to determine what kind of diet a person ate?
It can help anthropologists figure out when meat became a primary part of the ancient human diet or when marine resources began to be used.
Isotopic signatures
These variations in the ratios of isotopes of certain elements. If you ate and drank local water all of your life, your bones and teeth would have the same isotopic signature as the geographical region in which you lived
Why would an animal’s bones and teeth have different isotopic signatures?
If an individual has different isotopic signatures for their bones and teeth, it could indicate a migration some time during their life after childhood.
Mitochondrial DNA
What important conclusions were scientists about to make about Naia’s DNA?
recovered from a tooth indicates that Naia shares her DNA with modern Native Americans whose DNA has been linked conclusively to ancestors in Siberia
What methods did scientists use to analyze Naia’s remains and determine how many years ago she lived?
radiocarbon dating
mitochondrial DNA
