Index fossils and Embryos

There are three main pieces of evidence
that scientists use to prove evolution.

● Fossil evidence
● Comparative anatomy
● Embryology

Paleontology--The Study of Past Life

Paleontologists look
for fossils, or the
remains of ancient
organisms.

(they study fossils of
old dead things)

Fossils are formed when a plant or animal dies in a watery
environment and is buried in mud and silt quickly.

Fossil
formed
No
Fossil
formed

Fossils are rare

It is estimated that 1 in 80
million T-Rex became
fossilized. That is why
intact fossils are so
expensive.
($31.8 million)

Most of the
evidence for
Evolution of
organisms
comes from
fossils

Which organism lived the longest?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Multiple Choice

Which organism lived the longest?

• A

• B

• C

• D

Which organism lived the longest?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Which organism lived the longest?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Which organism lived the shortest amount
of time?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Multiple Choice

Which organism lived the shortest amount of time?

• A

• B

• C

• D

Which organism lived the shortest amount
of time?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Which organism went extinct?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Multiple Choice

Which organism went extinct?

• A

• B

• C

• D

Which organism went extinct?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Which organism is widely distributed?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Widely Distributed

Multiple Choice

Which organism is widely distributed?

• A

• B

• C

• D

Which organism is widely distributed?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Widely Distributed

Index fossils are:

Fossils of widely
distributed
organisms that lived
during only one
short time period.

An Index Fossil is widely distributed and short lived.

Widely Distributed

Short
Lived

Which organism would make the best index
Fossil?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Multiple Choice

Which organism would make the best index Fossil?

• A

• B

• C

• D

Which organism would make the best index
Fossil?

Fossil
Layer 5

Fossil
Layer 4

Fossil
Layer 3

Fossil
Layer 2

Fossil
Layer 1

A

B

C

D

Index Fossils
help tell how old
the rock around
it is

Through carbon
dating this index
fossil dates at
about 245 to 65
million years old.

Which suggest the rocks
around it are also 245 to
65 million years old.

So any other
fossils around
it would have
to be that old
also.

There are three main pieces of evidence
that scientists use to prove evolution.

● Fossil evidence
● Comparative anatomy
● Embryology

Cladogram
Activity

Multiple Choice

Which organisms are most closely related?

• 5 & 6

• 6 & 7

1. Which
organisms are
most closely
related?

a. 5 & 6

b. 6 & 7

1. Which
organisms are
most closely
related?

a. 5 & 6

b. 6 & 7

Evolution

Embryology

There are three main pieces of evidence
that scientists use to prove evolution.

● Fossil evidence
● Comparative anatomy
● Embryology

There are three main pieces of evidence
that scientists use to prove evolution.

● Fossil evidence
● Comparative anatomy
● Embryology

Evolution

(Embryology)

Embryology

(study of embryos)

Organisms that are closely related may also have

physical similarities before they are even born!

Embryo

em·bry·o

noun

an unborn or unhatched
offspring (baby) in the first
processes of
development.

Anatomy of an
Embryo
(parts)

Gills

Eye

Tail

Developmental Biology

• Embryology: The study of embryos, leading up to birth.

• Pharyngeal Pouches: A feature present in the embryos of vertebrates.

Which one of these is a human embryo?

​Which of these is a human embryo?

It could be because they all look a lot a like. Which is the point.
All mammals (including humans) start this way.

Comparative Embryology

Multiple Choice

The diagram illustrates an embryonic stage of two organisms.

Which of the following can be determined by observing the embryos shown in the diagram? 

• The organisms share a common ancestry.

• The organisms belong to the same mother.

• The organisms are native to the same geographic areas.

• The organisms will grow into anatomically similar adults.

Molecular Biology

• Molecular Biology: The study of gene structure and function.

• Comparing Sequences: An analysis of DNA Sequences across different species.

• Divergence: The idea that DNA mutations over time causes animals to be less related than others.

Multiple Choice

Scientists have found evidence that about 2.4 million years ago a gene regulating jaw muscles mutated and may have led to the more graceful human jaw we see today. The diagram below shows the skulls of 3 hominid species.

Which statement below most closely explains the link between jaw size and hominid evolution? 

• The jaws of hominids evolved to be smaller and less protruding over time.

• The jaws of hominids evolved to be larger and more protruding over time. 

• There appears to be no change in the jaws of hominids over time.

• The jaws of hominids changed over time due to a change in brain size. 

Fossil Evidence

We don’t see modern
animals in the fossil record.
We do see similar structured
fossils helping us concluded that there was a
change over
time.

Comparative
Anatomy

We see similar structures
with similar functions in animals
that are very
different; for example,
humans and bats. Animals and fossils that share
similar bone structures
help prove that they may still have a shared common ancestor.

Embryology

Every organism’s
embryos (first stages of a development) has gills, eyes, and tail regardless of whether or not they have
all those features when mature. But this
further proves that all to most things
all evolved from the same
common ancestor.

Multiple Choice

Similar patterns of embryological development provide further evidence that organisms have descended from totally separate and different ancestors.

• True

• False

Multiple Choice

What are the oldest fossils and why?

• B, C- because they are closest to the top

• A, B- because they are closest to the bottom

• They are all the same age- because they are all found on layer 2

• A, B- because they are found closest to the top

Multiple Choice

What conclusions can be made based on this table shown?

• the American black bear and the giant panda are most closely related

• the giant panda and the red panda are most closely related

• the red panda and the racoon are the most closely related

• the giant panda and the racoon are most closely related