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Presentation (evolution of whales)

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  • 1. Early Whales 1) Maiacetus Time 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. 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. 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.
  • 4. 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 .
  • 5. • 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.
  • 6. • 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.
  • 7. Summary picture