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Definitions
Geologic Time Scale
Grab Bag
Divisions of Geologic Time
Fossils
100
_________ is the death of every member of a species
What is extinction?
100
Name the time in Earth's history: Clue #1: 4.6 billion to 542 million years ago Clue #2: no Oxygen in air
What is Precambrian?
100
True/False: Humans have existed for most of Earth’s history.
False.
100
The largest division of geologic time are ______________.
What are eons?
100
How did scientists know what dinosaurs looked like?
They examine fossil evidence.
200
___________ is the extinction of many species at the same time
What is mass extinction?
200
Name the time in Earth's history: Clue #1: 251 million years ago Clue #2: Age of Reptiles
What is the Mesozoic era?
200
How is the geologic time scale of Earth’s history divided?
by major events or changes.
200
Eons are divided into __________.
What are eras?
200
The earliest fossils are of …
One-celled organisms
300
The age of an event or object in relation to other events or objects is called ______________
What is Relative age
300
Name the time in Earth's history: Clue #1: 65 million years ago to today Clue #2: fossils are in the top layer
What is the Cenozoic era?
300
True/False: Throughout Earth’s history, the number and type of life forms has remained fairly constant.
False.
300
Eras are divided into __________.
What are periods?
300
A fossil is an object that contains traces, remains, or evidence of ..
Living things from long ago
400
The oldest sections are shown on the __________, and the recent sections would be on the ________.
What is bottom/top?
400
Name the time in Earth's history: Clue #1: Humans first appeared
What is the age of mammals?
400
Mass extinction can happen when ..
Gradual changes in the climate or ocean currents OR huge events like a meteor falls from the sky and makes giant hole in the ground, kicking up dirt and soil into the air that blocks out the sun for a long time until plants die. Then when a lot of plants die, animals that eat plants have no food, and they die too.
400
Periods are divided into ____________.
What are epochs?
400
A well-known fossil group of extinct marine creatures that first appeared in the early Cambrian period.
What is the trilobite?
500
This event was the relatively rapid appearance (over a period of many millions of years) of many animal and plant species.
What is the Cambrian explosion?
500
The first trace of life on earth can be traced back to..
3.8 billion years ago.
500
Give an example of creatures that were victims of a mass extinction
What are dinosaurs?
500
There are _____ eons in Earth’s history.
What is four?
500
The soft parts of an organism often decay very quickly. The result is that many fossils..
Only preserve traces of the hard parts of the organism.