Chapter 14, Section 1, Life and Geologic Time
1) Units on the _____________ time scale are based on the appearance or
disappearance of the types of organisms that lived during that time.
2) Geologic time is divided into four major _____________________.
3) The _____________ is the longest subdivision and is based on an abundance
of fossils. We are currently in the Phanerozoic Eon in the Cenozoic Era.
4) _____________ are marked by major, striking worldwide changes in the types
of fossils that are present in rock, like the disappearance of certain species.
5) Eras are subdivided into ________________. _________________ are
based on types of life existing worldwide at a particular time.
6) Periods are subdivided into _______________. _____________ are
characterized by differences in life-forms, but differences can be regional
rather than global and can vary from continent to continent.
7) Only Epochs in the _________________ Era have been given specific names.
8) Geologic time can be subdivided only if ________ are present in rock records.
9) ________________ evolution means organisms have changed over time.
10) Changes in the environment can result in physical ______________ in species.
11) Species are groups of organisms that normally __________________ only
with other members of their group.
12) Darwin’s theory of natural ____________________ states that organisms
more adapted to an environment are more likely to survive and reproduce.
13) Natural selection within a species occurs only if characteristics present in
some of the members increase their chance of _________________.
14) ___________________ selection—breeding individuals with desired
characteristics; humans use this type of selection when breeding animals.
15) ________________ species can evolve from natural selection.
16) Trilobites have an ____________________ with three lobes, they lived in
oceans for more than 200 million years, and are considered an index fossil.
17) _______________ fossils are from organisms that were abundant, exhibited
specific characteristics that changed slowly through time, were widespread
geographically, and existed for a relatively short period of time.
18) Trilobite ____________ position changed as the species adapted to various
environments. The three lobed body of the trilobite did not change over time.
19) The trilobite exoskeleton and ________ changed in response to changing
environments and from having to compete for survival.
20) Continental collisions formed the giant landmass ________________ near
the end of the Paleozoic ____________, changing the trilobites environment.
21) These collisions may have dropped ___________________, causing the
extinction of trilobites.
Chapter 14, Section 2, Early Earth History
1) The __________________ time, from 4.5 billion to about 544 million years
ago, is the longest part of Earth’s history. During the first billion years there
was no life! Very few _______________________ remain from this time.
2) Many Precambrian rocks were deeply buried, causing the fossils in them to be
changed by ___________ and pressure, destroying any fossils they contained.
3) Most Precambrian organisms lacked _______ parts, so they didn’t form fossils.
4) Ancient __________________________ are layered mats of cyanobacteria.
5) Cyanobacteria are blue-green _________________, thought to be one of the
earliest life forms on Earth
6) Cyanobacteria contained _________________and used _______________ to
produce oxygen to add to the early Earth atmosphere.
7) Once oxygen was a major atmospheric gas, the ____________________ layer
developed, allowing more complex organisms to evolve.
8) Animals without backbones called ______________________ appeared late
in Precambrian time.
9) _____________________ organisms, similar to modern jellyfish, worms, and
corals was living during the Precambrian time.
10) The _________________ Era, 544 – 248 million years ago, had an abundance
of organisms with hard parts like shells and left us many more fossils.
11) Much of the planet was covered with warm, shallow seas so many of the trace
________________ were shells. __________________ were also common.
12) ___________________, animals with backbones, also evolved during this era.
13) ________________ might have evolved from fish with leg-like fins that
could get oxygen from the ________ with lungs or from the water with ____.
14) Some amphibians developed an egg with a membrane to keep it from drying out.
These eggs did not need to be laid in water and allowed __________ to evolve.
15) Reptiles also developed skin with hard scales that prevents them from losing
water, this let them survive in relatively ________________ climates.
16) _________________ evolved from amphibians to survive farther from water.
17) Several mountain-building episodes occurred during the Paleozoic Era because
of ______________ collisions.
18) The ___________Mountains were formed in several stages during this period.
19) Most marine and land species became ________________ at the end of the
Paleozoic Era.
20) ________________ was formed near the end of the Permian Period when
two continental plates came together.
21) 248 million years ago there was a mass _____________ that might have been
caused by changing climates or a large asteroid or comet collision with Earth.
Chapter 14, Section 3, Middle and Recent Earth History
1) The ______________________ Era lasted from 248 to 65 million years ago.
2) Pangaea separated into two landmasses during the _______________ period.
3) Plate tectonics separated Pangaea into _________________ in the north and
__________________________ in the south, both with drier climates.
4) __________________ evolved from reptiles during the Mesozoic Era. They
might have been warm-blooded, traveled in herds, and nurtured their young.
5) ______________, which scientists believe evolved from small, meat-eating
dinosaurs, first appeared during the Jurassic Period.
6) The earliest bird, ____________________, had wings and feathers but was
not a direct ancestor of today’s modern birds.
7) Small, mouse-like ________________, which are warm-blooded vertebrates
with hair and milk to feed their young, appeared in the Triassic Period.
8) Mammalian traits, being warm-blooded with hair and milk to feed their young,
allow them to survive in many changing _____________________.
9) _________________________, plants that produce seeds but not flowers,
appeared in the Paleozoic Era and dominated the land in the Mesozoic Era.
10) Pine trees and ginko trees are examples of _____________________ today.
11) Flowering plants, or____________________, appeared during the Cretaceous
Period. They have hard seed coats to protect the inside from the environment.
12) An angiosperm that developed during the Mesozoic Era is the ______ tree.
13) A great extinction, perhaps caused by a comet or an asteroid collision, occurred
about __________________ years ago, marking the end of the Mesozoic Era.
14) The ____________ Era began about 65 million years ago and continues today.
15) The Cenozoic Era is subdivided into two periods, the Tertiary Period and the
present day ______________ Period, which began about 1.8 million years ago!
16) Many _______________ formed, perhaps creating cooler climates worldwide.
The Alps, the Andes, and the Himalayas all formed during the Cenozoic Era.
17) Mammals continued to evolve. Ancestors of present day whales and dolphins,
_____________________ to live in the sea.
18) Many species became ____________ as the continents continued to separate.
19) Isolation of a species allows it to evolve separately from life-forms in other
parts of the world. Australia’s __________________ are a good example.
20) Homo sapiens, or _______________, appeared about 140,000 years ago
during the Mesozoic Era.