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

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? What size was it? What did it eat? Where did it live? With a partner, draw a quick sketch of the ancestor.

Scientists believe whales evolved from land mammals. VOCABULARY: Tetrapod - a 4-limbed organism (or an ancestor of one)

Check out this short animation showing how scientists believed whales evolved: http://collections.tepapa.govt.nz/exhibitions/whales/Segment.aspx?irn=161 6

Fossil records show these ancestors evolving over time. 7

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

DEFINITION: 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 organism over time. 9

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.

Scientists have studied whale evolution through fossils and DNA comparison.

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

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

Let’s Look at Ancient Ancestors

Sinonyx 65 Million Years Ago

Pakicetus 50 Million Years Ago

Ambulocetus 48 to 50 Million Years Ago

Indohyus 48 Million Years Ago

Rodhocetus 47 Million Years Ago

Basilosaurus 34 to 40 Million Years Ago

Dorudon 33 to 40 Million Years Ago

Adaptations 
 From Sinonyx to Humpback Whale

Adaptations 
 Streamlined Body

Adaptations 
 Forelimbs Modified Into Flippers

Adaptations 
 Tail Broadened Horizontally

Adaptations 
 Hind Limbs Disappeared Completely

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Adaptations 
 Blubber Instead of Hair

Adaptations 
 Nostrils on Top of Head

Adaptations 
 Highly Developed Hearing