Unformatted text preview: who wondered about the
evolutionary history of whales.
They clearly were mammals who had to breathe air. They were like seals and otters and walruses which
were specialized to live in the water.
But whales were the
of the group
How had they evolved? If their ancestors were land mammals,
we should expect that there were many transitional steps
between the land ancestors and today’s whales.
Those transitional species were missing until NOW. Whale Evolution Whale Phylogeny
Terrestrial Amphibious Aquatic Whale Phylogeny
Terrestrial Amphibious Aquatic TRENDS IN WHALE
EVOLUTION Whale Nostrils
Whale End of snout Middle of snout Top of head (Blowhole) Loss of Legs
50 mya Basilosaurus
37 mya Sperm Whale
Today Basilosaurus leg skeleton
Basilosaurus Evolution of
hears through ears directly Basilosaurus
vibrations transmitted by
lower jaw to middle ear
lower Modern toothed whale
sounds & lower jaw
receives Whale Evolution
Based on anatomy New Idea
Based on DNA...
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- Fall '07
- Evolution, transitional species