1WHEEEEE !

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What are we Doing Today?

•Whale fossil hunt•Whale ankle comparisons•Whale DNA comparisons•WHALE EVOLUTION

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Becoming Whales

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Diversity of Whales Today

Mysticetes (baleen whales):

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Diversity of Whales Today

Odontocetes (toothed whales):

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But Where Did They Come From?

ONE OF DARWIN’S IDEAS…

… I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.Charles Darwin, The Origin of Species, 1859 (first edition), Chapter 6: Difficulties on Theory

Darwin was wrong about the BEAR (he removed this idea in later editions), but spot-on with the process –

NATURAL SELECTION.

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Here’s a Peek into the Past…

So, Where DID Whales Come From?

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Moving in…

Notice that the earliest MAMMALS… were TERRESTRIAL - with LEGS !

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But WHALES SWIM;they DON’T WALK ON

LAND !

So - Where DID Whales Come From?

What would the earliest whales look

like?

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The Earliest MODERN WHALES…

65mya

NOW

MIOCENE

23 mya

Only go back toabout 23 mya…the beginning of the MIOCENE…

Great swimmers…

but NO WALKING

LEGS !

5 mya

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HOWEVER !

65mya

NOW

MIOCENE

23 mya

We DO have some whale-like fossils, with strange teeth,

from the EOCENE !

5 mya

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But… Where’s the Eocene?NOW

4.5bya

65mya

NOW

55 mya

34 mya

EOCENE

Miocene:Earliest modern whales

23 mya

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OK! So, where shall we look

forEocene Fossils?

The Tethys Sea

India Moved North…

…Squished into Asia…

Mountains of Pakistan

55

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Where shall we look?

Pakistan

Lots of exposed marine Eocene rocks in the Pakistan mountains

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Let’s Hunt Whale Fossils…

• Work in pairs• Open Your Eocene Timeline• Remove whale strips from plastic

bag• Listen for descriptions and timing• Place whale strip on timeline• Wait for next “discovery”

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Eocene Epoch Timeline

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Early Whale Teeth

~ 36 mya193

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in Dorudon

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

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Early Whale Teeth…

in a 4-legged mammal?

a Mesonychid - called Pachyaena

~ 55 mya… with tiny

hooves!

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

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Early Whale Teeth

Pakicetus - an early whale ~50 mya

1983 - Gingerich - Pakistan

WITH LEGS !

In Pakistan……and hooves, too!

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

Pakicetus 50 mya (1983 - Pakistan)

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Early whale teeth in…Basilosaurus ~37mya

and LEGS, too…

1990 Gingerich - Egypt

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

Pakicetus 50 mya (1983 - Pakistan)

Basilosaurus 37 mya (39-36 mya) 1990

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Early Whale Teeth

Rodhocetus - an early whale

~46 mya

early 1994 - Gingerich - Pakistan

And tiny hooves, too !

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

Pakicetus 50 mya (1983 - Pakistan)

Basilosaurus 37 mya (39-36 mya) 1990

Rodhocetus 46 mya (early 1994 - Pakistan)

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Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

Pakicetus 50 mya (1983 - Pakistan)

Basilosaurus 37 mya (39-36 mya) 1990

Rodhocetus 46 mya (early 1994 - Pakistan)

Transitional form? Predict What? (draw) Where?

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Early Whale Teeth… in Pakistan

Ambulocetus - the “walking whale”

~48 mya

late 1994 Thewissen

With tiny hooves, too !

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Eocene Epoch TimelineDorudon 36 mya (39-36 my) 1936

Pachyaena 55 mya (58-34 mya) 1955

Pakicetus 50 mya (1983 - Pakistan)

Basilosaurus 37 mya (39-36 mya) 1990

Rodhocetus 46 mya (early 1994 - Pakistan)

Ambulocetus 48 mya (late 1994 - Pakistan)

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Ambulocetus

Carl Buell

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Whale Phylogeny, 1994Hans Thewissen

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But Mesonychids are EXTINCT!

•Perissodactyls (odd-toed)

•Artiodactyls (even-toed)

Maybe Hooved Mammals?:

= Ungulates: Two Orders:

SO, Who are the Closest Living Relatives of

Whales?

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PerissodactylsOdd-Toed Ungulates

Horses & Zebras Rhinos & Tapirs

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ArtiodactylsEven-Toed Ungulates

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Leg Anatomy…

Heel Bone

Ankle Bone

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Ungulate Foot Bones…FOSSIL HORSE

Heel Bone

Ankle Bone

FOSSIL PIG

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Whale Ankles?

MesonychidPrim.Perissodactyl

Prim. Artiodactyl

Pakicetus

Pig

Compare ankle bones…

one big ridge

two small ridges

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Whale Phylogeny, 2001Philip Gingerich

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But WHICH Artiodactyls?

Will DNA Tell Us?

Let’s Compare DNA…

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DNA AnalysisCompare segments of beta-casein

gene

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DNA AnalysisCompare segments of beta-casein

gene

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DNA Differences

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DNA Differences

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DNA DifferencesFewer than five differences…

• 2 porpoise & sperm whale• 3 porpoise & right whale• 3 sperm whale & right whale• 3 sperm whale & hippo• 3 porpoise & hippo• 3 right whale & hippo• 3 giraffe & deer• 3 giraffe & cow• 4 cow & deer

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DNA DifferencesSeven differences…

• 7 pigs and peccaries

DNA DifferencesRemaining species…

Higher numbers - more distantly related

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Phylogenetic Tree - WHALES

Based on DNA Differences

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Provisional Phylogeny - Cetartiodactyls

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Whale Evolution Recap• Fossil teeth link whales to the 4-

legged mesonychids of the Paleo-Eocene

• Tiny hooves on mesonychids and early whale toes tie whales to the ungulates

• Ankle bones of early whales point to artiodactyl ungulates as the closest relatives of whales

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Whale Evolution Recap

• DNA confirms the artiodactyl connection and points to hippos as the closest cousins of whales

• Consilience: these multiple independent lines of evidence strengthen, narrow and confirm the hypothesized close relationship between whales and artiodactyls

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Whale’s Closest Cousin: Hippos

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53FAREWHALE!

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Have a Whale of a Time!

FINI