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Published byPaulina Clarke Modified over 9 years ago
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Alana and Annasimone
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Timeline 47 million years ago: - Alligator like feet - Fed in the water - 4.1 metres long - Forelimbs and hind limbs for walking - No tail flukes 48 million years ago: - 1.75 metres long - Nostrils were far forward - Forelimbs and hindlimbs function for walking - No tail flukes 46 million years ago: - Sea lion figure - Spent some time on land - 3 metres long - function for walking and swimming - Large hind limbs - No tail flukes 37 million years ago: - Completely aquatic - 4.5 metres long - Nostrils further back on skull - Forelimbs have become flippers - Elongation of the trunk - Reduced hind limbs - Tail flukes Present day: - Streamlined body - Insultating layer of blubber - Flippers as fore limbs - Hind legs are interbal vestiges - Tail is flattended horixontal flukes - No external neck - Large head and wide mouth 34 million years ago: - Completely aquatic - 9-10 metres long - Teeth reduced - First evidence of baleen for filter feeding - Nostrils further back on skull - Elbows immobile
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Since whales evolved from land mammals, at first their nostrils were positioned far forward.
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At one point, a mutation occurred, producing at least one whale with “nostrils” positioned further back along the snout. Nostrils
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This mutation helped that whale thrive in a sea environment by easing the process of surfacing for air.
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The mutated whale survived, thrived and reproduced, passing on this favourable characteristic to its offspring.
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This mutation became more common among the population
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Modern whales are now born with “nostrils” (blowholes) on their backs
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