Download - Presentation (evolution of whales)
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EVOLUTION OF WHALES
JOURNEY THROUGH SEAS AND
OCEANS
Click on the
whale for FUN
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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 .
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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 “
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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.
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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 .
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• 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.
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• 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.
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Summary picture
Summary Picture
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