Download Chapter 10 Vocabulary List

Chapter 10 Vocabulary List
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Geologic Time Scale—division of Earth’s history into time units based largely on
the types of life-forms that lived only during certain periods
Eons—longest subdivision in the geologic time scale that is based on the
abundance of certain types of fossils and is subdivided into eras, periods, and
epochs
Era—Second-longest division of geologic time; is subdivided into periods and is
based on major worldwide changes in types of fossils
Periods—units of geologic time characterized by the types of life existing
worldwide at the time; is subdivided into epochs
Epochs—next-smaller division of geologic time after the period; is characterized
by differences in life-forms that may vary regionally
Organic Evolution—change of organisms over geologic time
Species—a group of organisms that normally reproduces only with other
members of their group
Natural Selection—process by which organisms that are suited to a particular
environment are better able to survive and reproduce than organisms that are not
(The strongest survive)
Trilobite—organism with a three-lobed exoskeleton that was abundant in
Paleozoic oceans and is considered to be an index fossil
Pangaea—large, ancient landmass that was composed of all the continents joined
together
Precambrian Time—the longest part of Earth’s history; includes the Hadean,
Archean, and Proterozoic Eons
Cyanobacteria—blue-green algae thought to be one of the earliest forms of life on
Earth
Paleozoic Era—era of ancient life; 544 million years ago-248 million years ago
Mesozoic Era—era of middle life; between 248 and 65 million years ago; marked
by rapid movement of Earth’s plates
Cenozoic Era—era of recent life; began 65 million years ago and continues today;
divided into the Tertiary and Quaternary periods; features periods of mountain
building