Developing a Geologic Time Line
Response to Change
Late Paleozoic
Mesozoic Life
Geology of the Cenozoic Era
100

___ are the largest unit of the geologic time.

Eons

pg. 363

100

A  ___ is the extinction of many species on Earth within a short period.

Mass Extinction

pg. 365

200

The Phanerozoic eon began ____ million years ago.

541 

pg. 363

200

Many things can cause ___ changes.

Climate

pg. 365

200

In the Late ___, some fishlike organisms spent part of their lives on land.

Paleozoic

pg. 374

200
Scientists hypothesized that some __ are more closely related to the present-day birds.

Dinosaurs

pg. 382

200

Its fossils and its ___ record are better preserved.

It's rocks

pg. 387

M
e
n
u