Definitions
_________ is the death of every member of a species.
What is extinction?
Name the time in Earth's history. Clue #1: 4.6 billion to 542 million years ago. Clue #2: No oxygen in atmosphere.
What is the Precambrian?
___________ is the extinction of many species at the same time.
What is mass extinction?
Name the time in Earth's history. Clue #1: 251 million years ago. Clue #2: Age of Reptiles.
What is the Mesozoic era?
How is the geologic time scale of Earth’s history divided?
By major events or changes, often mass extinctions.
The earliest fossils are of _________.
Single-celled organisms (prokaryotes).
The age of an event or object in relation to other events or objects is called ______________
What is 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.
What is the Cenozoic era?
A fossil is an object that contains traces, remains, or evidence of ______________.
Living things from long ago.
According to this Law, the oldest sections are shown on the bottom, and the recent sections would be on the top.
What is the Law of Superposition?
Name the time in Earth's history. Clue #1: Humans first appeared
What is the Cenozoic era (or the 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.
These are the criteria fossils must meet in order to be considered index fossils.
Wide-spread geographically, abundant, easily recognizable, and short-lived.
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?
The first trace of life on earth can be traced back to __________.
About 3.8 billion years ago (or the Archaean eon). Precambrian is too broad.
There are _____ eons in Earth’s history.
What is two?
This fossil is useful for dating and correlating the strata in which it is found.
What are index fossils?