Chapter 14 Flashcards
Division of Earth’s history into time units based largely on the types of life-forms that lived only 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 world wide 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 that organisms that are not
Natural Selection
Organism with a three-lobed exoskeleton that was abundant in Paleozoic oceans and is considered to be an index fossil
Trilobite
Large, ancient landmass that was composed of all the continents joined together
Pangaea
Longest part of Earth’s history, lasting from 4.0 billion to about 544 million years ago
Precambrian Time
Chlorophyll-containing, photosynthetic bacteria thought to be one of Earth’s earliest life-forms
Cyanobacteria
Era of ancient life, which began about 544 billion years ago, when organisms developed hard parts, and ended with mass extinctions about 245 million years ago
Paleozoic Era
Middle era of Earth’s history, during which Pangaea 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
