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Show me the intermediate fossils! - Richard Dawkins

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Richard Dawkins Show me the intermediate fossils! People often say, " Where are the intermediate fossils?" "Show us intermediate fossils." THERE ARE PLENTY OF INTERMEDIATE FOSSILS, AND ONE OF THE BEST EXAMPLES IS WHALES. THE MODERN WHALES ARE UP THERE. HERE'S A SERIES OF FOSSILS BACK IN TIME: DORUDON ABOUT 36 MILLION YEARS AGO, RODHOCETUS ABOUT47 1/2 MILLION YEARS, PAKICETUS ABOUT 48 1/2 MILLION YEARS. AND YOU CAN SEE THEY FORM A LOVELY SERIES OF INTERMEDIATES. AS YOU GO FROM OLD TO YOUNG, PAKICETUS, RODHOCETUS, YOU'RE GRADUALLY LOSING THE HIND LEGS TO DORUDON, WHICH HAS ALMOST LOST THE HIND LEGS COMPLETELY? MODERN WHALES HAVE COMPLETELY LOST THE HIND LEGS. THERE ARE SOME VESTIGIAL BONES, SOME REMNANT BONES BURIED DEEP INSIDE THE BODY. A LOVELY SERIES OF INTERMEDIATES GETTING PROGRESSIVELY MORE AND MORE SPECIALIZED IN LIVING IN THE SEA. IF YOU LOOK AT PAKICETUS, WHICH IS AN OLD FOSSIL WHALE, YOU SEE THAT THE NOSTRILIS JUST ABOUT WHERE YOU'D EXPECT THE NOSTRIL TO BE, NEAR THE TIP OF THE SNOUT. IF WE MOVE ON A MILLION YEARS TO RODHOCETUS, YOU SEE THAT THE NOSTRIL HAS MOVED BACKWARDS, BACKWARDS ON THE SKULL, BACKWARDS ALONG THE SNOUT. NOW IF YOU LOOK AT A MODERN WHALE-- THAT'S A DOLPHIN, A MODERN DOLPHIN-- YOU SEE THAT THE NOSTRIL IS RIGHT UP NEAR THE TOP OF THE HEAD? THAT'S THE BLOW HOLE. THE NOSTRIL HAS MOVED RIGHT BACKWARDS. NOW, A REALLY SURPRISING THING IS WHICH ANIMAL IS THE MOST CLOSELY RELATED TO MODERN WHALES AMONG MODERN ANIMALS, AND THE ANSWER, ASTONISHINGLY, IS THE HIPPOPOTAMUS, WHICH IS CLASSIFIED IN THE EVEN-TOED UNGULATES, THE CLOVEN-HOOFED ANIMALS. SO WHAT WE NOW BELIEVE IS THAT THERE WAS AN ANCESTOR, WHICH WAS A CLOVEN HOOFED ANIMAL, BEFORE 55 MILLION YEARS AGO. A LITTLE BIT BEFORE THAT, THE ANCESTOR GAVE RISE TO OTHER CLOVEN-HOOFED ANIMALS. AND THEN LATER THAN THAT, THERE WAS A SPLIT BETWEEN THE LINEAGE LEADING TO WHALES AND THE LINEAGE LEADING TO MODERN HIPPOPOTAMUSES. IT'S MOLECULAR EVIDENCE AS WELL AS FOSSIL EVIDENCE THAT SHOWS THAT HIPPOS ARE THE MOST CLOSELY RELATED MODERN ANIMALS. Brian Kim

Video Details

Duration: 2 minutes and 33 seconds
Country: South Korea
Language: English
Views: 371
Posted by: pound on Nov 1, 2010

Richard Dawkins shows how whales evolved from a cloven-hoofed ancestor, and reveals whales' closest modern-day cousin.

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