Definitions
_________ is the death of every member of a species
extinction
Name the time in Earth's history: Clue #1: 4.6 billion to 542 million years ago Clue #2: no Oxygen in air
Precambrian
True/False: Humans have existed for most of Earth’s history.
False.
The largest division of geologic time are ______________.
eons
How did scientists know what dinosaurs looked like?
fossil evidence
___________ is the extinction of many species at the same time
mass extinction
Name the time in Earth's history: Clue #1: 251 million years ago Clue #2: Age of Reptiles
Mesozoic era
Eons are divided into __________.
eras
The earliest fossils are of …
One-celled organisms
The age of an event or object in relation to other events or objects is called ______________
Relative age
Name the time in Earth's history: Clue #1: 65 million years ago to today Clue #2: fossils are in the top layer
Cenozoic era
Eras are divided into __________.
periods
A fossil is an object that contains traces, remains, or evidence of ..
Living things from long ago
The oldest sections are shown on the __________, and the recent sections would be on the ________.
bottom/top?
Name the time in Earth's history: Clue #1: Humans first appeared
age of mammals
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.
Periods are divided into ____________.
epochs
A well-known fossil group of extinct marine creatures that first appeared in the early Cambrian period.
trilobite
This event was the relatively rapid appearance (over a period of many millions of years) of many animal and plant species.
Cambrian explosion
The first trace of life on earth can be traced back to..
3.8 billion years ago.
Give an example of creatures that were victims of a mass extinction
dinosaurs
There are _____ eons in Earth’s history.
four
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.