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WHEEEEE !

WHEEEEE !. HOW HAVE WHALES EVOLVED?. Whale fossil Whale ankle comparisons Whale DNA comparisons WHALE EVOLUTION. Becoming Whales. Diversity of Whales Today. Mysticetes (baleen whales):. Diversity of Whales Today. Odontocetes (toothed whales):. But Where Did They Come From?.

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WHEEEEE !

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  1. WHEEEEE !

  2. HOW HAVE WHALES EVOLVED? • Whale fossil • Whale ankle comparisons • Whale DNA comparisons • WHALE EVOLUTION

  3. Becoming Whales

  4. Diversity of Whales Today Mysticetes (baleen whales):

  5. Diversity of Whales Today Odontocetes (toothed whales):

  6. But Where Did They Come From? ONE OF DARWIN’S IDEAS… … I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale. Charles Darwin, The Origin of Species, 1859 (first edition), Chapter 6: Difficulties on Theory • Darwin was wrong about the BEAR(he removed this idea in later editions), but correct about the process – NATURAL SELECTION.

  7. So, Where DID Whales Come From? Here’s a Peek into the Past…

  8. Moving in… Notice that the earliest MAMMALS… were TERRESTRIAL - with LEGS !

  9. But WHALES SWIM;they DON’T WALK ON LAND! So - Where DID Whales Come From? What did the earliest whales look like?

  10. The Earliest MODERN WHALES… NOW Only go back toabout 23 mya…the beginning of the MIOCENE… 5 mya MIOCENE 23 mya Great swimmers… but NO WALKING LEGS ! 65mya

  11. HOWEVER ! We there are some whale-like fossils, with strange teeth, NOW 5 mya MIOCENE 23 mya from the EOCENE ! 65mya

  12. But… Where’s the Eocene? NOW NOW Miocene:Earliest modern whales 23 mya 34 mya EOCENE 55 mya 4.5bya 65mya

  13. OK! So, where shall we look forEocene Fossils? 38 Mountains of Pakistan The Tethys Sea 55 India Moved North… …Squished into Asia…

  14. Where shall we look? Pakistan Lots of exposed marine Eocene rocks in the Pakistan mountains

  15. Let’s Hunt Whale Fossils… • Work in pairs • Open Your Eocene Timeline • Remove whale strips from plastic bag • Listen for descriptions and timing • Place whale strip on timeline • Wait for next “discovery”

  16. Eocene Epoch Timeline

  17. Early Whale Teeth in Dorudon ~ 36 mya 1936

  18. Eocene Epoch Timeline Dorudon36 mya (39-36 my) 1936

  19. Early Whale Teeth…in a 4-legged mammal? a Mesonychid - called Pachyaena ~ 55 mya … with tiny hooves!

  20. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Pachyaena55 mya (58-34 mya) 1955

  21. Early Whale Teeth WITH LEGS ! …and hooves, too! In Pakistan… Pakicetus - an early whale ~50 mya 1983 - Gingerich - Pakistan

  22. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Pakicetus50 mya (1983 - Pakistan) Pachyaena 55 mya (58-34 mya) 1955

  23. Early whale teeth in… Basilosaurus ~37mya and LEGS, too… 1990 Gingerich - Egypt

  24. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Basilosaurus37 mya (39-36 mya) 1990 Pakicetus 50 mya (1983 - Pakistan) Pachyaena 55 mya (58-34 mya) 1955

  25. Early Whale Teeth Rodhocetus - an early whale And tiny hooves, too ! ~46 mya early 1994 - Gingerich - Pakistan

  26. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Basilosaurus 37 mya (39-36 mya) 1990 Rodhocetus46 mya (early 1994 - Pakistan) Pakicetus 50 mya (1983 - Pakistan) Pachyaena 55 mya (58-34 mya) 1955

  27. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Basilosaurus 37 mya (39-36 mya) 1990 Rodhocetus 46 mya (early 1994 - Pakistan) Transitional form? Predict What? (draw) Where? Pakicetus 50 mya (1983 - Pakistan) Pachyaena 55 mya (58-34 mya) 1955

  28. Early Whale Teeth… in Pakistan With tiny hooves, too ! Ambulocetus - the “walking whale” ~48 mya late 1994 Thewissen

  29. Eocene Epoch Timeline Dorudon 36 mya (39-36 my) 1936 Basilosaurus 37 mya (39-36 mya) 1990 Rodhocetus 46 mya (early 1994 - Pakistan) Ambulocetus48 mya (late 1994 - Pakistan) Pakicetus 50 mya (1983 - Pakistan) Pachyaena 55 mya (58-34 mya) 1955

  30. Ambulocetus Carl Buell

  31. Whale Phylogeny, 1994Hans Thewissen

  32. But Mesonychids are EXTINCT! SO, Who are the Closest Living Relatives of Whales? • Perissodactyls (odd-toed) • Artiodactyls (even-toed) Maybe Hooved Mammals?: = Ungulates: Two Orders:

  33. PerissodactylsOdd-Toed Ungulates Rhinos & Tapirs Horses & Zebras

  34. ArtiodactylsEven-Toed Ungulates

  35. Leg Anatomy… Heel Bone Ankle Bone

  36. Ungulate Foot Bones… FOSSIL HORSE FOSSIL PIG Heel Bone Ankle Bone

  37. Pig Whale Ankles? Compare ankle bones… Pakicetus two small ridges Mesonychid Prim. Artiodactyl Prim.Perissodactyl one big ridge

  38. Whale Phylogeny, 2001Philip Gingerich

  39. But WHICH Artiodactyls? Will DNA Tell Us? Let’s Compare DNA…

  40. DNA AnalysisCompare segments of beta-casein gene

  41. DNA AnalysisCompare segments of beta-casein gene

  42. DNA Differences

  43. DNA Differences

  44. DNA DifferencesFewer than five differences… • 2 porpoise & sperm whale • 3 porpoise & right whale • 3 sperm whale & right whale • 3 sperm whale & hippo • 3 porpoise & hippo • 3 right whale & hippo • 3 giraffe & deer • 3 giraffe & cow • 4 cow & deer

  45. DNA DifferencesSeven differences… • 7 pigs and peccaries DNA DifferencesRemaining species… Higher numbers - more distantly related

  46. Phylogenetic Tree - WHALESBased on DNA Differences

  47. Provisional Phylogeny - Cetartiodactyls

  48. Whale Evolution Recap • Fossil teeth link whales to the 4-legged mesonychids of the Paleo-Eocene • Tiny hooves on mesonychids and early whale toes tie whales to the ungulates • Ankle bones of early whales point to artiodactylungulates as the closest relatives of whales

  49. Whale Evolution Recap • DNA confirms the artiodactyl connection and points to hippos as the closest cousins of whales • Consilience: these multiple independent lines of evidence strengthen, narrow and confirm the hypothesized close relationship between whales and artiodactyls

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