EVOLUTION OF WHALES

JOURNEY THROUGH SEAS AND

OCEANS

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Early Whales1) MaiacetusTime period : 49 - 40 millon years ago• Maiacetus probably spent much of its life in the water

, returning to land only to mate and give birth.

• It had flipper like limbs , similar to those of a modern sea or walrus and like some seals .

2) Basilosaurus cetoides

Time period : 40 - 35 millon years ago• With a streamlined body and paddle-like forelimbs

show Basilosaurus was a fast swimmer. • Small hind limbs reveal that it descended from land –

dwellers . Scientists first thought that it was a reptile and had named it “regal lizard “

3) Llanocetus denticrenatus

Time Period : 35 – 30 million years ago • A skull from the oldest known filter feeding whale

revealed an intermediate step in the evolution of mysticeti (baleen whales) .

• Its teeth and”baleen” formed a sieve that kept tiny plankton in while letting water out.

Whales- a brief synopsis

• Whales swim , but their ancestors walked .

• All modern mysticetes are large filter-feeding or baleen whales, though the exact means by which baleen is used differs among species .

• All cetaceans, including whales, dolphins and porpoises, are descendants of land-dwelling mammals of the Artiodactyl order (even-toed ungulates).

• Both are related to the Indohyus, an extinct semi-aquatic deer-like ungulate, from which they split around 54 million years ago.

 

• These primitive cetaceans first took to the sea about 50 million years ago and became fully aquatic about 5–10 million years later.

• Their features became adapted for living the marine environment.

Summary picture

Summary Picture

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