1. Chapter 14 The History of Life
Section 1: Fossil Evidence of Change
Section 2: The Origin of Life

2. Earth formed about 4.6 billion years ago.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Land Environments
Earth formed about 4.6 billion years ago.
Gravity pulled the densest elements to the center of the planet.
After about 500 million years, a solid crust formed on the surface.

3. 14.1 Fossil Evidence of Change
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Atmosphere
The gases that likely made up the atmosphere are those that were expelled by volcanoes.
Water vapor (H2O)
Carbon dioxide (CO2)
Sulfur dioxide (SO2)
Carbon monoxide (CO)
Hydrogen sulfide (H2S)
Hydrogen cyanide (HCN)
Nitrogen (N2)
Hydrogen (H2)

4. A fossil is any preserved evidence of an organism.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Clues in Rocks
A fossil is any preserved evidence of an organism.
Most organisms decompose before they have a chance to become fossilized.

5. 14.1 Fossil Evidence of Change
Chapter 14
The History of Life
14.1 Fossil Evidence of Change

6. Nearly all fossils are formed in sedimentary rock.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Fossil Formation
Nearly all fossils are formed in sedimentary rock.
The sediments build up until they cover the organism’s remains.
Minerals replace the organic matter or fill the empty pore spaces of the organism.

7. Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Dating fossils
Relative dating is a method used to determine the age of rocks by comparing them with those in other layers.

8. Uses the decay of radioactive isotopes to measure the age of a rock
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Radiometric Dating
Uses the decay of radioactive isotopes to measure the age of a rock
Radioactive isotopes that can be
used for radiometric dating are found only in
igneous or metamorphic rocks.

9. The Geologic Time Scale
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
The Geologic Time Scale
The geological time scale is a model that expresses the major geological and biological events in Earth’s history.
Divided into 4 eras: the Precambrian era, the
Paleozoic era, the Mesozoic era, and the
Cenozoic era
Each era is divided into PERIODS
Each era is divided into one or more periods.

10. Autotrophic prokaryotes enriched the atmosphere with oxygen.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Precambrian
Nearly 90 percent of Earth’s entire history, stretching from the formation of Earth to the beginning of the Paleozoic era about 542 million years ago
Autotrophic prokaryotes enriched the atmosphere with oxygen.
By the end of this era (~ 544 mya) multicellular eukaryotes, such as sponges and jellyfish filled the oceans

11. The first tetrapods emerged in the Devonian.
Chapter 14
The History of Life
The Paleozoic Era
The ancestors of most major animal groups diversified in what scientists call the Cambrian explosion.
Life in the oceans continued to evolve at the end of the Cambrian period.
Fish, land plants, and insects appeared during the Ordovician and Silurian periods.
The first tetrapods emerged in the Devonian.

12. About 90% of marine species and 70% of land species disappeared
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
The largest mass extinction ended the Paleozoic era at the end of the Permian period.
About 90% of marine species and 70% of land species disappeared
Between 60 and 75 percent of the species
alive went extinct.

13. About 65 million years ago, a meteorite struck Earth.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
The Mesozoic Era
Mammals and dinosaurs first appeared late in the Triassic period, and flowering plants evolved from nonflowering plants.
The middle of this era is called the Jurassic period (~208 mya) which is referred to as the Age of the Dinosaurs
Birds evolved from a group of predatory dinosaurs in the middle of the Jurassic period.
About 65 million years ago, a meteorite struck Earth.

14. Chapter 14
The History of Life
14.1 Fossil Evidence of Change
Plate tectonics describes the movement of several large plates that make up the surface of Earth.
These plates, some of which contain continents, move atop a partially molten layer of rock underneath them.

15. Mammals became the dominant land animals.
Chapter 14
The History of Life
14.1 Fossil Evidence of Change
The Cenozoic Era
Mammals became the dominant land animals.
After the mass extinction at the end of the Mesozoic era, mammals of all kinds began to diversify.
The modern human species appeared perhaps as recently as 200,000 years ago

16. Life requires proteins.
Chapter 14
The History of Life
14.2 The Origin of Life
Making Proteins
Life requires proteins.
One possible mechanism for the formation of proteins would be if amino acids were bound to a clay particle.

17. Some RNA sequences appear to have changed very little through time.
Chapter 14
The History of Life
14.2 The Origin of Life
Genetic Code
Some RNA sequences appear to have changed very little through time.
Many biologists consider RNA to have been life’s first coding system.
Other researchers have proposed that clay crystals could have provided an initial template for RNA replication.

18. Scientists hypothesize that the first cells were prokaryotes.
Chapter 14
The History of Life
14.2 The Origin of Life
Cellular Evolution
Scientists hypothesize that the first cells were prokaryotes.
Many scientists think that modern prokaryotes called archaea are the closest relatives of Earth’s first cells.

19. Photosynthesizing Prokaryotes
Chapter 14
The History of Life
14.2 The Origin of Life
Photosynthesizing Prokaryotes
Archaea are autotrophic.
They do not obtain their energy from the Sun.
Archaea also do not need or produce oxygen.

20. Chapter 14
The History of Life
14.2 The Origin of Life
Many scientists think that photosynthesizing prokaryotes evolved not long after the archaea.
Prokaryotes, called cyanobacteria, have been found in rocks as old as 3.5 billion years.

21. Chapter 14
The History of Life
14.2 The Origin of Life

22. Which is an example of the theory of spontaneous generation?
Chapter 14
The History of Life
Chapter Diagnostic Questions
Which is an example of the theory of
spontaneous generation?
Tadpoles become frogs.
A starfish can grow from a severed arm.
Damp hay and corn create mice.
From a tiny acorn, an oak can grow. A B C D
CDQ 1

23. What gas do scientists think was absent from Earth’s early atmosphere?
Chapter 14
The History of Life
Chapter Diagnostic Questions
What gas do scientists think was absent from
Earth’s early atmosphere?
sulfur
nitrogen
oxygen
water vapor A B C D
CDQ 2

24. In which period did the first land vertebrates appear?
Chapter 14
The History of Life
Chapter Diagnostic Questions
In which period did the first land vertebrates
appear?
Cambrian
Devonian
Triassic
Mesozoic A B C D
CDQ 3

25. In which type of rock do paleontologists search for fossils?
Chapter 14
The History of Life
14.1 Formative Questions
In which type of rock do paleontologists search
for fossils?
igneous
metamorphic
sedimentary
volcanic A B C D
FQ 1

26. Which dating method determines the age of
Chapter 14
The History of Life
14.1 Formative Questions
Which dating method determines the age of
rocks by comparing them to rocks in other
layers?
absolute dating
geological dating
relative dating
sedimentary dating A B C D
FQ 2

27. Which geological change during the Mesozoic
Chapter 14
The History of Life
14.1 Formative Questions
Which geological change during the Mesozoic
era had the greatest effect in shaping the
course of evolution?
plate tectonics
extensive glaciation
increased volcanic activity
meteorite impact A B C D
FQ 3

28. At one time people believed that mold growing
Chapter 14
The History of Life
14.2 Formative Questions
At one time people believed that mold growing
on a piece of cheese was created by the
cheese. This is the idea of __________.
biogenesis
transgenesis
primordial generation
spontaneous generation A B C D
FQ 4

29. Which is the half-life of the radioactive isotope shown in the graph?
Chapter 14
The History of Life
Chapter Assessment Questions
Which is the half-life of the radioactive isotope shown in the graph?
18 years
36 years
54 years
72 years A B C D
CAQ 1

30. Which factor made it unlikely that life existed on
Chapter 14
The History of Life
Standardized Test Practice
Which factor made it unlikely that life existed on
Earth 4 billion years ago?
absence of oxygen
absence of food
intense heat
intense sunlight A B C D
STP 1

31. Chapter 14
The History of Life
Standardized Test Practice
Why do scientists believe that archea are the closest relatives to Earth’s first cells?
They are eukaryotes.
They contain DNA.
They carry out photosynthesis.
They live in extreme environments. A B C D
STP 6

32. Section 1 Vocabulary fossil paleontologist relative dating half-life
Chapter 14
The History of Life
Vocabulary
Section 1
fossil
paleontologist
relative dating
half-life
geologic time scale
era
period
Cambrian explosion
plate tectonics

33. Section 2 Vocabulary spontaneous generation Chapter 14
The History of Life
Vocabulary
Section 2
spontaneous generation