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Whale Evolution - PowerPoint PPT Presentation

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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