Chapter 14 Earth Science Geologic Time
Words to Know – Section 1 Life and Geologic Time Geologic time scale Eon Era Period Epoch Organic evolution Species Natural selection Trilobite Pangea
Division of Earth’s history into time units based largely on the types of life-forms that lived during certain periods. Geologic time scale
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. eon
Second-longest division of geologic time; is subdivided into periods and is based on major worldwide changes in types of fossils era
Third-longest division of geologic time; is subdivided into epochs and is characterized by the types of life that existed worldwide. period
Next-smaller division of geologic time after the period; is characterized by differences in life-forms that may vary regionally. epoch
Change of organisms over geologic time Organic evolution
Group of organisms that reproduces only with other members of their own group species
Process by which organisms that are suited to a particular environment are better able to survive and reproduce than organisms that are not Natural selection
Organism with a three-lobed exoskeleton that was abundant on Paleozoic oceans and is considered to be an index fossil trilobite
Large ancient landmass that was composed of all the continents joined together Pangea
Words to Know – Section 2 Early Earth History Precambian time Cyanobacteria Paleozoic Era
Longest part of Earth’s history, lasting from 4 Longest part of Earth’s history, lasting from 4.0 billion to about 544 million years ago Precambrian time
Chlorophyll-containing, photosynthetic bateria thought to be one of Earth’s earliest life-forms cyanobacteria
Era of ancient life, which began about 544 million years ago, when organisms developed hard parts, and ended with mass extinctions about 245 million years ago Paleozoic Era
Words to Know – Section 3 Middle and Recent Earth History Mesozoic Era Cenozoic Era
Middle era of Earth’s history, during which Pangea broke apart, dinosaurs appeared, and reptiles and gymnosperms were the dominant land life-forms Mesozoic Era
Era of recent life that began about 66 million years ago and continues today; includes the first appearance of Homo sapiens about 400,000 years ago Cenozoic Era