chapter 17 -1 the fossil recod – Flashcards
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paleontologists
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scientists who study fossils
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fossil record
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information about past life, including the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived
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extinct
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no longer existing or living
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relative dating
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method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock
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index fossils
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distinctive fossil used to compare the relative ages of fossils
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half-life
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the time required for one half of the atoms of a radioisotope to emit radiation an decay products
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radioactive dating
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the use of half-lives to determine the age of a sample
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geologic time scale
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scale used by paleontologists to represent evolutionary time
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eras
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one of several subdivisions of the time between the Precambrian and the present
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periods
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subdivisions of eras
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proteinoid microspheres
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large organic molecules that form tiny bubbles
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microfossils
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microscopic fossils of unicellular prokaryotic organisms that resemble modern bacteria have been found in rocks more than 3.5 billion of years old.
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endosymbiotic theory
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theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms
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mass extinction
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event in which many types of living things become extinct at the same time
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macroevolution
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large-scale evolutionary changes that take place over long periods of time
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adaptive radiation
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process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms
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convergent evolution
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the process by which unrelated species become more similar as they adapt to the same kind of environment
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coevolution
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process by which two species evolve in response to changes in each other
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punctuated equilibrium
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pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
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what is the fossil recored
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the fossil record provides evidence about the history of life on earth.it also shows how different groups of organisms,including specie, have changed
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what do paleontologist do?
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They collect fossils and infer what past life forms were like.
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what does yhe fossil tecord reveal"
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...provides evidence about the history of life on earth. It also shows how different groups of organisms, including species, have changed over time.
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Describe how most fossils are formed?
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Most fossils are formed in sedimentary rocks. And the particles are carried by streams and rivers into lakes or seaswhere they eventually settle to the bottoms.
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How is sedementary rock formed?
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It is formed whenexposure to rain, heat, wind and cold breaks down existing rock into small particles of sand, silt, and clay.
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Why is the fossil record described as an incomplete record of lifes history?
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Because the formation of any fossil depends upon the precise combination of conditions. For every organism that leaves a fossil, many more die without leaving a trace.
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what do paleontologist do when they study fossils?
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They unearth the remains of entire organisms. Sometimes they reconxtruct an extinct species from a few fossil bits, the look foranatomical differences and similarities betwwen the fossil and the living organism.
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Name two techniques that paleontologist use to determine the age of fossils.
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...relative dating and radioactive dating
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Radioactive decay
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the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
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What two things do researchers compare to determine when an organism lived?
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By comparing carbon 14 which begins to decay when a thing dies to carbon 12 which is not radioactive and does not decay, scientist can determine when a organism lived.
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What does geologic time represent?
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It represents evolutionary time.
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What does geologic time begin with?
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Precambrian time which civers about 88% of the earths history.
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Identify three eras that geologist use to divide time?
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Paleozoic Mesozoic Cenozoic
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Paleozoic era
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Began 544 million years ago and is the period in which many vertebrates and invertebrates lived.
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Mesozoic era
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middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants
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Cenozoic era
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the latest of the four eras into which geologic time is subdivided ; 65 million years ago to the present: sometimes called the age of the mammels.
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What type of dating provides abosulte age for a given fossil?
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Radioactive dating
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How are eras and periods related?
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Eras are subdivided into periods which range in lenght frim tens of millions of years toless than two million years.
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How do fossils form?
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Most fossils form when organisms that die become buried in sediments.
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What geologic era is known as the age of mammals?
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Cenozoic
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Identify the three periods included in mesiozoic era.
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Triassic Jurassic Cretaceous
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Cambrian period
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from 544 million to about 500 million years ago
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Identify the six periods that existed during the paleozoic era.
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Cambrian Ordovician Silurian Devonian Carboniferous Permian
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Identify the two periods during the cenozoic era.
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Quaternary Tertiary
