Name: _____________________________
Geologic Time Scale Practice
1.) Put the following organisms in order of when they appeared on Earth.
Geologic Time (pages 100-101):
2.) Geologic time is divided into units based on ______________.
a.) geologic changes
b.) fossils and rocks
c.) type of life-forms living during certain periods
d.) all of these
3.) One of the larger units of time based on changes in the types of fossils present in rock is
known as _________________. ( based on when animals first appeared)
3.) The unit of time is based on types of life living worldwide is known as ______________.
4.) The smallest unit of time that represents changes in living things on continents is known as
____________________.
Precambrian Time (pages 108-110):
5.) Very few _______________ remain from this time because most Precambrian organisms
lacked _____________ parts.
6.) Cyanobacteria are blue-green ______________. They are one of the __________ life
forms to appear. These organisms added ______________ to the atmosphere through
photosynthesis.
7.) During much of the Precambrian Time the planet was lifeless and covered with
_________________.
8.) At the end of Precambrian time, animals were similar to modern ____________________,
________________ and ______________ were living. All of these animals do not have
backbones and are known as ________________.
Paleozoic Era (pages 110-114)
9.) Many organisms with _________________ and vertebrates lived in the warm, shallow seas.
The first vertebrates were similar to ______________.
10.) _________________ began to appear and were able to live in water and on land.
11.) The ______________________ mountains formed when volcanic islands and the African
plate collided with the North American plate.
12.) Near the end of the Era, the major Super continent named ___________________ was
formed
Mesozoic Era (pages 116-119)
13.) ________________ broke up into different continents.
14.) ______________ evolved; they might have been warm-blooded, traveled in herds and
nurtured their young.
15.) ________________ appeared during the Jurassic period.
16.) _________________ plants appeared during this Era.
17.) A great extinction was thought to be caused by a(n) ______________ which hit Earth.
Cenozoic Era (pages 120-121)
18.) Many ________________ ranges were formed and maybe caused cooler climates.
19.) Mammals continued to develop on Earth due to the large amounts of ______________.
20.) Homo sapiens, or __________________ appeared on Earth.