Geologic Time

The longest interval of time is called _________.

An eon

The atmosphere was filled with poisonous gas during the:

Archean Eon

Proterozoic Eon

Buildup of oxygen; first eukaryotes.

Phanerozoic Eon

Current eon

Longest interval of geologic time.

Eon

Major divisions of geologic time within each eon; identified by major changes in the fossil record.

Era

A cell that has complex internal structures, such as a nucleus; e.g., plant and animal cells.

Eukaryotic

Hadean Eon

Formation of the solar system.

The solar system developed during the:

Hadean Eon

Why do some people argue that the Cenozoic era should not be called the "Age of Mammals"?

Insects are equally as abundant during this era; birds are just as widespread as mammals during this era; and flowering plants are just as common during this era.

Paleozoic Era

Largest mass extinction in Earth's history.

What do scientists use to divide the geologic time scale?

Major divisions in the fossil records.

You wake up and find yourself surrounded by ferns, trees, flying birds, and different types of dinosaurs. Which era did you wake up in?

Mesozoic

Which of the following events define the Proterozoic eon?

Oxygen builds up in atmosphere; eukaryotic cells first seen; and stable continents.

The era that is defined by both a huge explosion in the diversity of life as well as the largest mass extinction is __________.

Paleozoic

Major divisions of geologic time within each era; identified by changes in the fossil record.

Period

A simple cell that lacks complex internal structures, e.g., bacterial cells.

Prokaryotic

Cenozoic Era

Sometimes called "Age of Mammals".

Fossil mounds made of ancient photosynthetic bacteria.

Stromatolites

Mesozoic Era

Time of the dinosaurs.

Archean Eon

Toxic atmosphere; first bacteria.