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Geologic Time

ch 4 Brechbill

species Group of organisms that only reproduce with members of their own group
cyanobacteria Earliest form of life. Blue-green algae that photosynthesized.
gymnosperm Plants that produce seeds but not flowers.
angiosperm Plants that have flowers
geologic time scale Divisions of earth's history into time units
trilobite Index fossil that has three lobes, and a segmented body
pangaea large, ancient landmass that contained all continents. Formed in the Paleozoic and broke up in the Mesozoic.
Cenozoic Era of recent life. Began 66 million years ago.
Paleozoic Era of ancient life; dominated by fish and ended with a great mass extinction
Precambrian Longest time of earth's history. Lasted nearly 4 billion years.
Mesozoic Era of middle life. Pangaea broke apart, dominated by reptiles & dinosaurs.
organic evolution Changes of organisms over time
eon longest subdivision of geologic time
era second longest subdivision of geologic time, based on worldwide fossil changes.
period These subdivisions are divided into epochs
epoch smallest division of geo time.
natural selection Process by which only the organism that are suited for an environment will survive. "Survival of the fittest"
Created by: brechbillc