Biology; Chapter 17: The History Of Life Vocabulary

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scientist who studies fossils.  
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.
fossil record
term used to refer to a species that has died out.
method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock.
relative dating
distinctive fossil used to compare the relative ages of fossils.
index fossil
length of time required for half of the radioactive atoms in a sample to decay.
technique in which scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains.
radioactive dating
scale used by paleotologists to represent evolutionary time.
geologic time scale
one of several subdivisions of the time between the Precambrian and the present.
unit of time into which eras are subdivided.
tiny bubble, formed of large organic molecules, that has some characteristics of a cell.
proteinoid microsphere
microscopic fossil; ______ of single-celled prokaryotic organisms that resemble modern bacteria have been found in rocks more than 3.5 billion years old.
theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms.
endosymbiotic theory
event in which many types of living things become extinct at the same time.
mass extinction
large-scale ecolutionary changes that take place over long periods of time.
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.
adaptive radiation
process by which unrelated organisms independently evolve similarities when adapting to similar environments.
convergent evolution
process by which two species evolve in response to changes in each other.
pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change.
punctuated equilibrium