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Whale Evolution

Whale Evolution. by William T. Kratz. Evolution of the Whale. historical research of the whale fossil records related species geographic distribution whale evolution video. Whale Researchers. In 1693 John Ray classified whales as mammals

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Whale Evolution

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  1. Whale Evolution by William T. Kratz

  2. Evolution of the Whale • historical research of the whale • fossil records • related species geographic distribution • whale evolution video

  3. Whale Researchers • In 1693 John Ray classified whales as mammals • In 1859 Charles Darwin believes that whales have similarities to the black bear • In 1883 William Flower suggested whales evolved from ungulates • Philip D. Gingerich Ph.D. researched whale fossils in Pakistan and Egypt from1970s through 1990s • Hans Thewissen led the team that reconstructed the skeleton of the first land mammal ancestor of the whale

  4. Ancestors of Modern Whales • Indohyus • Pakicetus • Ambulocetus natans • Rodhocetus • Basilosaurus • Dorudon

  5. Indohyus • Indohyus literally means India’s Pig • Fossil founded by Indian geologist Ranga Rao • Skeleton assembled by Hans Thewissen • Fossil dates back 60 mya • Even toed ungulate • Size of a modern house cat • Chemical tests on teeth and bone analysis revealed that Indohyus spent much of its time wadding in water as a hippo would • Bone structure around the ear revealed unique similarities to that of the modern whale

  6. Pakicetus • First Archaeocete • Evolved 52 mya • Founded by Philip Gingerich in 1983 in Pakistan • Pakicetus was about the size of a wolf • Primarily was a land mammal but spent much time in the water. • Had sharp teeth of a carnivore • Like Indohyus, had similar bone structure around ear to that of modern whales

  7. AmbulocetusNatans • Ambulocetus “walking whale” was found in 1992 by Thewissen • Fossil dates back 49 mya • 3 meters in length, hind legs were well adapted for swimming • Skeleton suggests that it hunted like a crocodilian • Ambulocetus had no external ear, probably kept head close to ground to detect vibrations of land prey • Anatomy of spinal column-swam with tail going up and down • Had an adaptation in the nose that enabled it to swallow underwater, and its periotic bones had a structure like those of whales, enabling it to hear well underwater

  8. Rodhocetus • 49-43 mya in Pakistan by Stromer 1908 • Lumbar vertebrae-neural spines higher, more developed tail for swimming • Sacral vertebrae not fused- more flexibility, body developed for swimming • Femur was a third shorter than that of the Ambulocetus’ • Skull elongated • Ears pushed further back • Smaller eyes • First ancestor to be more water orientated that land

  9. Basilosaurus • Basilosaurus “regal lizard” • First skeletal parts found in Louisiana and Alabama in the 1830’s • Fossil dates back 35-40 mya • Could grow up to 20 meters • First ancestor that was all aquatic • Complete set of hind limb bones and a pelvis, but very small • Formation of blow hole-single large nostril to the top of the head • First to have tail fluke- due to structure of vertebral proportions

  10. Dorudon • Dorudon was founded by Gingerich in 1994 • Fossil dates back 33-40 mya • Found in North America, India, and Pakistan • Originally thought to be an intermediate Basilosarus, ranging from 4-5 meters • Carnivorous, feeding on small fish and mollusks • Looked very similar to modern whales, but lacked the melon organ • Also a completely water orientated mammal.

  11. Geographic Distribution • Distribution of Basilosaurus and Dorudon widely spread vs. Ambulocetus and Rodhocetus restricted to one area in India, Pakistan region

  12. Whale Evolution Video • http://www.youtube.com/watch?v=lUuUEo84YlY&feature=related • WHALE EVOLUTION ANIMATION

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