1. Clues About Evolution
Section 2

2. Clues From
Fossils

3. How do fossils form?

4. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.

5. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.
It includes the following conditions:

6. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.
It includes the following conditions:
rapid and permanent
burial/entombment
protecting the specimen
from environmental or
biological disturbance

7. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.
It includes the following conditions:
rapid and permanent continued sediment
burial/entombment accumulation as opposed to
protecting the specimen an eroding surface
from environmental or ensuring the organism remains
biological disturbance buried in the long-term

8. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.
It includes the following conditions:
rapid and permanent continued sediment
burial/entombment accumulation as opposed to
protecting the specimen an eroding surface
from environmental or ensuring the organism remains
biological disturbance buried in the long-term
oxygen deprivation
limiting the extent of
decay and also biological
activity/scavenging

9. How do fossils form?
Fossilization - a variety of complex processes
that preserve organic remains within the
geological record.
It includes the following conditions:
rapid and permanent continued sediment
burial/entombment accumulation as opposed to
protecting the specimen an eroding surface
from environmental or ensuring the organism remains
biological disturbance buried in the long-term
oxygen deprivation absence of excessive heating
limiting the extent of or compression
decay and also biological which might otherwise destroy
activity/scavenging the remains

10. How do fossils form?

11. How do fossils form?
Fossil evidence is typically
preserved within sediments

12. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water

13. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?

14. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?

15. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?
The conditions
listed on the
previous slide
occur more
frequently
beneath water

16. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?
The conditions
listed on the
previous slide
occur more
frequently
beneath water

17. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?
The conditions The majority of
listed on the the Earth's
previous slide surface is
occur more covered by water
frequently (70%+)
beneath water

18. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?
The conditions The majority of
listed on the the Earth's
previous slide surface is
occur more covered by water
frequently (70%+)
beneath water

19. How do fossils form?
Fossil evidence is typically
preserved within sediments
beneath water
Why?
The conditions The majority of Even fossils derived
listed on the the Earth's from land, including
previous slide surface is dinosaur bones were
occur more covered by water ultimately preserved
frequently (70%+) in sediments
beneath water deposited beneath
water

20. How do fossils form?

21. How do fossils form?

22. How do fossils form?
Fossilization can also occur on land, but is
rare.

23. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?

24. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?

25. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?
specimens that
undergo
mummification
in a cave or
desert

26. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?
But...
specimens that
undergo
mummification
in a cave or
desert

27. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?
But...
specimens that
undergo
mummification
in a cave or
desert

28. How do fossils form?
Fossilization can also occur on land, but is
rare.
How?
But...
specimens that In reality these examples
undergo are only a delay of
mummification decomposition rather
in a cave or than a lasting mode of
desert fossilization

29. A fish returns to its birth place to
spawn.

30. Having spawned the fish dies and
shortly after sinks to the seafloor.

31. After several weeks the soft body
tissues have mostly decayed.

32. Tectonic activity induces nearby
sediment to mobilize, burying the fish
in the event.

33. Several months pass and all that
remains of the buried fish is its
skeleton.

34. As times passes more sediment
accumulates above the fish and the
skeleton is gradually compressed and
permineralized.

35. Over time the rock is distorted and
uplifted by geological forces associated
with continental movement, raising it
above sea level.

36. The uplifted rock is exposed to
weathering and gradually erodes away,
eventually exposing the tip of the fish's
skull at the surface.

37. A paleontologist recognizes the fish by
the small area of skull exposed and
begins to carefully extract the
specimen.

38. A Pomognathus fish from Houghton
Quarry - the skull is clearly visible, and
what parts of the skeleton remain are
obscured within the chalk matrix.

39. Types of Fossils
Mineralized Fossils
Minerals replace wood or bone to create
a piece of petrified wood or mineralized
bone fossil.

40. Types of Fossils
Imprint Fossil
A leaf, feather, bone or entire
body can leave an imprint on
sediment that later hardens to
become rock.

41. Types of Fossils
Cast Fossil
Minerals can fill in the hollows of animal
tracks

42. Types of Fossils
Frozen Fossils
The remains of an organism can be trapped
in ice that remains frozen for thousands of
years.

43. Types of Fossils
Fossil in Amber
When the sticky resin of certain cone-bearing
plants hardens over time, amber forms.

45. Most fossils are found in sedimentary
rocks.

46. Most fossils are found in sedimentary
rocks.
Sedimentary rocks:
formed when layers of sand, silt, clay, or
mud are compacted and cemented
together, or when minerals are deposited

47. How Old?

49. Paleontologists use two basic methods,
either together or alone, to determine the
age of a fossil:

50. Paleontologists use two basic methods,
either together or alone, to determine the
age of a fossil:
relative dating

51. Paleontologists use two basic methods,
either together or alone, to determine the
age of a fossil:
relative dating

52. Paleontologists use two basic methods,
either together or alone, to determine the
age of a fossil:
relative dating radiometric dating

53. Paleontologists use two basic methods,
either together or alone, to determine the
age of a fossil:
relative dating radiometric dating

54. relative dating

55. based on the idea that in
relative dating undisturbed areas, younger
rock layers are deposited on
top of older rock layers.

56. based on the idea that in
relative dating undisturbed areas, younger
rock layers are deposited on
top of older rock layers.
provides only an estimate of
a fossil’s age

57. based on the idea that in
relative dating undisturbed areas, younger
rock layers are deposited on
top of older rock layers.
provides only an estimate of
a fossil’s age
estimate is made by
comparing the ages of rock
layers above and below the
fossil layer

59. radioactive elements give
off a steady amount of
radiation as it slowly
changes to a nonradioactive
element

60. radioactive elements give
off a steady amount of
radiation as it slowly
changes to a nonradioactive
element
the age is estimated by comparing
the amount of radioactive element
with the amount of nonradioactive
element in the rock

61. radioactive elements give
off a steady amount of
radiation as it slowly
changes to a nonradioactive
element
the age is estimated by comparing
the amount of radioactive element
with the amount of nonradioactive
element in the rock
this method does not always
produce exact results, because the
original amounts of radioactive
element in the rock can never be
determined

62. radiometric radioactive elements give
off a steady amount of
dating radiation as it slowly
changes to a nonradioactive
element
the age is estimated by comparing
the amount of radioactive element
with the amount of nonradioactive
element in the rock
this method does not always
produce exact results, because the
original amounts of radioactive
element in the rock can never be
determined

63. Radioactive Decay
an unstable nucleus loses energy by emitting
ionizing particles and radiation.
Carbon 14

64. Radioactive Decay
an unstable nucleus loses energy by emitting
ionizing particles and radiation.
Carbon 14
6 protons
8 electrons
trace amounts on Earth
– less than 1 ppt
(0.0000000001%)

65. Radioactive Decay
an unstable nucleus loses energy by emitting
ionizing particles and radiation.
Carbon 14
6 protons
8 electrons
trace amounts on Earth
– less than 1 ppt
(0.0000000001%)

66. Radioactive Decay
an unstable nucleus loses energy by emitting
ionizing particles and radiation.
Carbon 14
6 protons
8 electrons
trace amounts on Earth
– less than 1 ppt
(0.0000000001%)

67. Radioactive Decay
This decay, or loss of energy, results in an
atom of one type transforming to an atom of
a different type.
Carbon 14
6 protons
8 electrons
trace amounts on Earth
– less than 1 ppt
(0.0000000001%)

69. Half life of carbon-14 is 5,730 ± 40 years. It can
only accurately measure up to 60,000 years.

70. Half life of carbon-14 is 5,730 ± 40 years. It can
only accurately measure up to 60,000 years.
The method of dating does not always produce exact
results, because the original amount of radioactive
element in the rock can never be determined for
certain.

71. Fossils and Evolution

72. Fossils and Evolution
Fossils provide a record of organisms that
lived in the past.

73. Fossils and Evolution
Fossils provide a record of organisms that
lived in the past.
However, the fossil record is incomplete, it
has gaps.

74. Fossils and Evolution
Fossils provide a record of organisms that
lived in the past.
However, the fossil record is incomplete, it
has gaps.
The gaps exist because most organisms do
not become fossils.

75. Green Egg and Ham
 I am Sam  Would you like them
Sam I am Here or there?
That Sam-I-am I would not like them
That Sam-I-am! here or there.
I do not like I would not like them
that Sam-I-am anywhere.
I do not like
Do you like green eggs and ham.
green eggs and ham I do not like them,
Sam-I-am
I do not like them, Would you like them
Sam-I-am. in a house?
I do not like Would you like them
green eggs and ham. with a mouse?
.

76. Fossils and Models

77. Fossils and Models
Scientists can use fossils to make models that
show what the organisms might have looked
like.

78. Fossils and Models
Scientists can use fossils to make models that
show what the organisms might have looked
like.
From fossils, scientists can sometimes
determine
whether the organisms lived in family groups
or alone
what types of food they ate
what kind of environment they lived in

79. Direct Evidence for Evolution

80. Direct Evidence for Evolution
Plant breeders observe evolution when
they use cross-breeding to produce
genetic changes in plants.

81. Direct Evidence for Evolution
Plant breeders observe evolution when
they use cross-breeding to produce
genetic changes in plants.
The development of antibiotic resistance in
bacteria is another direct observation of
evolution.

82. Direct Evidence for Evolution
Plant breeders observe evolution when
they use cross-breeding to produce
genetic changes in plants.
The development of antibiotic resistance in
bacteria is another direct observation of
evolution.
Scientists have noted similar rapid
evolution of pesticide-resistant insect
species.

83. Indirect Evidence for Evolution

84. Indirect Evidence for Evolution
Similarities in embryo structures

85. Indirect Evidence for Evolution
Similarities in embryo structures
Chemical makeup of organisms including
DNA
the way organisms develop into adults

86. Indirect Evidence for Evolution
Similarities in embryo structures
Chemical makeup of organisms including
DNA
the way organisms develop into adults
Indirect evidence does not provide proof of
evolution, but it does support the idea.

87. Embryology

88. Embryology
The study of embryos and their
development.

89. Embryology
The study of embryos and their
development.
A tail and pharyngeal pouches are found at
some point in the embryos of fish, reptiles,
birds, and mammals.

90. Embryology
The study of embryos and their
development.
A tail and pharyngeal pouches are found at
some point in the embryos of fish, reptiles,
birds, and mammals.
Fish develop gills, but the other organisms
develop other structures.

91. Embryology
The study of embryos and their
development.
A tail and pharyngeal pouches are found at
some point in the embryos of fish, reptiles,
birds, and mammals.
Fish develop gills, but the other organisms
develop other structures.
Fish, birds, and reptiles keep their tails,
but many mammals lose theirs.

92. Embryology
The study of embryos and their
development.
A tail and pharyngeal pouches are found at
some point in the embryos of fish, reptiles,
birds, and mammals.
Fish develop gills, but the other organisms
develop other structures.
Fish, birds, and reptiles keep their tails,
but many mammals lose theirs.
These similarities suggest an evolutionary
relationship among all vertebrate species.

94. Homologous Structures

95. Homologous Structures
Body parts that are similar in origin and
structure are called homologous. They can
also be similar in function.

96. Homologous Structures
Body parts that are similar in origin and
structure are called homologous. They can
also be similar in function.
They often
indicate that
two or more
species share
common
ancestors.

97. Vestigial Structures

98. Vestigial Structures
Vestigial structures —structures that
don’t seem to have a function.

99. Vestigial Structures
Vestigial structures —structures that
don’t seem to have a function.
Vestigial structures also provide
evidence for evolution.

100. Vestigial Structures
Vestigial structures —structures that
don’t seem to have a function.
Vestigial structures also provide
evidence for evolution.
Scientists hypothesize that vestigial
structures are body parts that once
functioned in an ancestor.

101. Vestigial Structures
Vestigial structures —structures that
don’t seem to have a function.
Vestigial structures also provide
evidence for evolution.
Scientists hypothesize that vestigial
structures are body parts that once
functioned in an ancestor.
Appendix

102. Our Appendix ~ Useful after
The US scientists This function has been made obsolete by modern,
found that the industrialised society; populations are now so
appendix acted as a dense that people pick up essential bacteria from
"good safe house" for each other, allowing gut organisms to regrow
bacteria essential for without help from the appendix, the researchers
healthy digestion, in said.
effect re-booting the But in earlier centuries, when vast tracts of land
digestive system after were more sparsely populated and whole regions
the host has could be wiped out by an epidemic of cholera, the
contracted diseases appendix provided survivors with a vital individual
such as amoebic stockpile of suitable bacteria.
dysentery or cholera, "The function of the appendix seems related to the
which kill off helpful massive amount of bacteria that populates the
germs and purge the human digestive system," said Bill Parker, a
gut. professor of surgery and one of the scientists
responsible for establishing its status as a useful
http://www.independent.co.uk/life-style/health-and-families/health-news/the-appendix-does-have-a-use--rebooting-the-gut-396277.

103. DNA

104. DNA
Scientists compare DNA from living
organisms to identify similarities among
species.

105. DNA
Scientists compare DNA from living
organisms to identify similarities among
species.
Examinations of ancient DNA often
provide additional evidence of how some
species evolved from their extinct
ancestors.

106. DNA
Scientists compare DNA from living
organisms to identify similarities among
species.
Examinations of ancient DNA often
provide additional evidence of how some
species evolved from their extinct
ancestors.
By looking at DNA, scientists also can
determine how closely related organisms
are.

107. DNA
Scientists compare DNA from living
organisms to identify similarities among
species.
Examinations of ancient DNA often
provide additional evidence of how some
species evolved from their extinct
ancestors.
By looking at DNA, scientists also can
determine how closely related organisms
are.
For example, DNA studies indicate that
dogs are the closest relatives of bears.