Whale Evolution 1 Whales and dolphins are mammals. They are some - - PowerPoint PPT Presentation

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Whale Evolution 1 Whales and dolphins are mammals. They are some - - PowerPoint PPT Presentation

May 09, 2023 140 likes •458 views

Whale Evolution 1 Whales and dolphins are mammals. They are some of the only mammals that live in water. 2 What do you think the ancestor of modern day whales were like? 3 If whales evolved from one common ancestor, what did it look like?

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Whale Evolution

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Whales and dolphins are mammals. They are some of the only mammals that live in water.

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What do you think the ancestor of modern day whales were like?

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If whales evolved from one common ancestor, what did it look like? What size was it? What did it eat? Where did it live?

With a partner, draw a quick sketch of the ancestor.

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Scientists believe whales evolved from land mammals.

VOCABULARY: Tetrapod - a 4-limbed

  • rganism (or an

ancestor of one)

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Check out this short animation showing how scientists believed whales evolved:

http://collections.tepapa.govt.nz/exhibitions/whales/Segment.aspx?irn=161

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Fossil records show these ancestors evolving over time.

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The different species that existed on the journey from ancient land mammal to whale are called TRANSITIONAL FORMS

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Transitional forms are evolutionary steps an organism goes through as it transitions from one set of adaptations to

  • another. Transitional forms

show adaptations as they appear (or disappear) from an

  • rganism over time.

DEFINITION:

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A transitional form is a species that shows an organism TRANSITIONING into something new. Through fossils, they show the slow changes in body structures over millions of years.

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Scientists have studied whale evolution through fossils and DNA comparison.

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Why do you think the ancestors of whales returned to the sea?

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Watch this short video:

http://museumvictoria.com.au/melbournemuseum/discoverycentre/600-million- years/videos/whale-evolution/

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Let’s Look at Ancient Ancestors

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Sinonyx

65 Million Years Ago

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Pakicetus

50 Million Years Ago

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Ambulocetus

48 to 50 Million Years Ago

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Indohyus

48 Million Years Ago

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Rodhocetus

47 Million Years Ago

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Basilosaurus

34 to 40 Million Years Ago

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Dorudon

33 to 40 Million Years Ago

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Adaptations


From Sinonyx to Humpback Whale

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Adaptations


Streamlined Body

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Adaptations


Forelimbs Modified Into Flippers

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Adaptations


Tail Broadened Horizontally

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Adaptations


Hind Limbs Disappeared Completely

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Adaptations


Blubber Instead of Hair

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Adaptations


Nostrils on Top of Head

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Adaptations


Highly Developed Hearing