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May 10, 2017 Aims:

SWBAT analyze and evaluate the scientific evidence provided

by the fossil record.

Agenda

1. Do Now

2. Class Notes

3. Guided Practice

4. Independent Practice

5. Practicing our AIMS:

E.3-Examining Evidence

How will you help our class earn all of our S.T.R.I.V.E. Points?

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Aim Check:

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OBJECTIVES: By the end of class, students will be able to…

SWBAT analyze and evaluate the scient ific evidence provided by the fossil record.

DO NOW 1. The diagram below shows a population of adult giraffes over time. Letters A, B, and C represent

three time periods. Use Darwin’s theory to explain what has occurred over the generations.

2. Brainstorm how the fossil record could be used as evidence to support the theory of evolution.

SCIENCE 8

Examining

Ev idence

E.3

Name: _____________________________

Date: ________________________________

Homeroom: _________________________

Evolution

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CLASS NOTES

EVOLUTIONARY EVIDENCE EVIDENCE #1: COMPARATIVE ANATOMY

What it is

COMPARATIVE ANATOMY:

_________________________________________________________________

_________________________________________________________________

What it means

Whales: Mammals or Fish?

Part icular

details

HOMOLOGOUS STRCUTURES:

_________________________________________________________________

_________________________________________________________________

o Whales, bats, hippos, and people all have the same bones in their

front appendages

EVIDENCE #2: EMBRYOLOGY

What it is

EMBRYOLOGY:

_________________________________________________________________

_________________________________________________________________

What it means

Dolphins vs Humans

Part icular

details

Studying the embryological development of liv ing things provides clues to

the evolution of present-day organisms.

During some stages of development, organisms exhibit ancestral features in

whole or incomplete form.

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EVIDENCE #3: FOSSIL RECORD

What it is

FOSSIL RECORD:

_________________________________________________________________

_________________________________________________________________

What it means

No legs or 4 legs?

Part icular

details

TRANSITIONAL FORMS:

_________________________________________________________________

_________________________________________________________________

EVIDENCE #4: DNA

What it is

DNA:

_________________________________________________________________

_________________________________________________________________

What it means

Common Ancestor?

Part icular

details

COMMON ANCESTOR:

_________________________________________________________________

_________________________________________________________________

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INDEPENDENT PRACTICE

Directions: Summarize what you learned today in the space below. You may use

words, pictures, charts, or a combination of these.

Focus on the following for your summary:

What ev idence do scientists use to determine common ancestors among species?

Explain how each type of ev idence is used to demonstrate evolution.

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Case study: Land-living ancestors of whales Fossils offer crucial clues for evolution, because they reveal the often remarkable forms of creatures long

vanished from Earth. Some of them even document evolution in action, recording creatures moving

from one environment to another.

Whales, for example, are beautifully adapted to life in water, and have been for millions of years. But,

like us, they are mammals. They breathe air, and give birth to and nurse live young. Yet there is good

evidence that mammals originally evolved on land. If that is so, then the ancestors of whales must have

transitioned to the water at some point.

As it happens, we have numerous fossils

from the first ten million years or so of

whale evolution. These include several

fossils of aquatic creatures such as

Ambulocetus and Pakicetus, which have

characteristics now seen only in whales —

especially in their ear anatomy — but also

have limbs like those of the land-living

mammals from which they are clearly

derived.

In 2007, scientists identified a possible link

between land mammals and whales.

Called raoellids, these now-extinct

creatures would have looked like very

small dogs, but were more closely related

to hooved animals — the group that

includes modern-day cows, sheep, deer,

pigs and hippos. Scientists found that

molecular evidence also suggests a deep

evolutionary connection between whales

and these hooved animals. One raoellid,

Indohyus, is similar to whales but has some

differences (ears, teeth, bone thickness)

from hooved animals. These indicators

suggest that this raccoon-sized creature

spent much of its time in water. Therefore,

Indohyus could be the transition organism

between land and sea.

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1. What is the claim being made in the text and what evidence supports this claim?

2. Interpret the fossil record shown in the case study, which indicates the evolution of the modern

whale. Note at least two specific changes in the structure/characteristics over time.

3. The passage states that molecular evidence was used to support the connection between whales

and hooved animals. Identify the type of molecular evidence we have learned about that can be

used to indicate relationships.

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The forelimbs below all have a similar structure (A), yet each

one is found in a different species (Bird, bat, cat, whale, and

human).

These structures are known as HOMOLOGOUS STRUCTURES, or

body parts with similar structures found in different species.

The word homologous, coined in about 1656, derives from the

Greek homologos, where homo = same and logos =

relationship. Homologous structures can indicate evolutionary

relationships between organisms.

4. Scientists use both the fossil record and homologous

structures as evidence that evolution occurs. Fossils are

remnants of skeletons from ancient organisms that are

preserved underground. When a scientist examines

homologous structures they might also look at bones, but

how are homologous structures DIFFERENT from fossils?

5. What does it mean if species are said to have “common ancestors”?

6. Take a closer look at the bone from the whale. Notice that whales, like humans, have five finger like

structures inside their fin. How does this homologous structure help support the theory of evolution?

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Acanthostega, an

early tetrapod

HIGH SCHOOL CHALLENGE

From Water to Land: Our Finned Ancestors The animals we are most familiar with are tetrapods — they are vertebrates (they have

backbones), four limbs, and they live on land. That includes humans, almost all domestic

animals and most of the wild ones that any child would recognize: mammals, birds,

amphibians and reptiles. The vast majority of vertebrates, however, are not tetrapods, but fish.

There are more kinds of fish, in fact, than all the species of tetrapods combined. Evolutionary

Biologists believe that all life actually began in the sea. Indeed, through the lens of evolution,

tetrapods (humans and most other animals) are just one branch of the fish family tree! In other

words, tetrapods are the relatives of fish but happen to be adapted for life out of water.

The first transition from water to land took place more than 360 million years ago. I t was one of

the most demanding such moves ever made in the history of life. How did fins become legs?

And how did the transitional creatures deal with the demands of land life, from the dry

environment to the weight of gravity?

I t used to be thought that the first land creatures were stranded fish that

evolved to spend more and more time ashore, returning to water only to

reproduce. Over the past 20 years, palaeontologists have uncovered fossils

that have turned this idea upside down. The earliest tetrapods, such as

Acanthostega from around 365 million years ago, had fully formed legs, with

toes, but retained internal gills. These gills would have soon dried out if this creature was on

land for a prolonged period of time. This lead scientists to believe that fish evolved legs long

before they came on land! The earliest tetrapods did most of their evolving in the more

forgiv ing aquatic environment. Coming ashore seems to have been the very last stage of their

evolution.

Researchers suspect that all tetrapods evolved from creatures called elpistostegids. These very

large, carnivorous, shallow-water fish would have looked and behaved much like alligators, or

giant salamanders. They looked like tetrapods in many respects, except that they still had fins.

Until recently, elpistostegids were known only from small fragments of fossils that were poorly

preserved, so it has been hard to get a rounded picture of what they were like. In the past

couple of years, several discoveries from northern Canada have changed all that. In 2006,

Edward Daeschler and his colleagues described spectacularly well- preserved fossils of an

elpistostegid known as Tiktaalik. This new fossil allow us to build up a good picture of an

aquatic predator with distinct similarities to tetrapods — from its flexible neck, to its very limb-

like fin structure.

Elpistostegid: This is a computer rending that

scientists were able to produce from the Tktaalik

fossil of an Elpistostegid

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1. What is a tetrapod in your own words? Also provide an example of a tetrapod that is not mentioned

in the text.

2. How did scientists’ theory about the evolution of tetrapods change with the finding of the

Acanthostega fossil? What evidence did they find that refuted their initial hypothesis?

3. Tetrapods such as humans, cows, and lizards are all extremely different organisms. However,

according to the fossil record all they share a common ancestor . In other words, all tetrapods evolved

from the same ancient organism. What is the common ancestor of humans, cows, and lizards

according to the text?

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Science 8

E.3:

Examining Evidence

Name: _____________________________

Date: _______________________________

Homeroom: _________________________

Quick Notes:

SKILL SNAPSHOT

Like A Scholar?

Yes No

Redo?

Yes No

1. Scientists call the fossil pictured a “transitional fossil” because it has characteristics of both dinosaurs

and birds. How does this fossil serve as evidence for the theory of evolution?

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Directions: Answer each multiple choice question. Once you have selected the best answer, justify your reasoning

in the text box.

Your justification needs to be in complete sentences and use ev idence from today’s packet.

2. Several species of extinct giant tortoise lived on different islands in the Indian Ocean. One species is

still alive on Aldabra Island. The shells and skins of the extinct tortoises are in museums and can be

studied.

What is the most accurate way to find out how closely related the living one is to the extinct one?

A. Search the history records of what the extinct tortoises look like.

B. Compare the bones and shells of the extinct tortoises to each other.

C. Measure the distance between Aldabra and the other islands.

D. Compare the DNA of all the tortoise species, extinct and living.

3. Fossils of the Coelacanth fish occur in the fossil record from 410 to 65 million years ago. The lack of

more recent fossils led scientist to conclude that the fish went extinct along with the dinosaurs. In

1983, a fisherman caught a living Coelacanth.

More than 200 of them have been caught on the deep reefs in the Indian Ocean. This fish has been

called a “living fossil” because its body plans in nearly identical to the 400 million year old fossils.

This structural similarity supports which statement?

A. The environment of the deep sea has changed little over millions of years.

B. The amount of salt in the deep sea has varied greatly over millions of years.

C. The oceans have completely dried up multiple t imes during the past 400 million years.

D. The oceans have been continuously repopulated by freshwater fish species over millions of

years.