How whales’ ancestors left land behind

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By moving into the water full-time, the ancestors of whales paved the
way for their descendants to become behemoths, largely free from
gravity’s constraints. Today, the blue whale is the largest animal ever
to live.

But even before the move, this lineage was setting size records. One ancient cousin to modern whales and hippos, called Andrewsarchus mongoliensis,
ranks as the largest mammal known to have stalked the land as a
predator. A skull from this creature, the only fossil found so far from
this beast, greets visitors on their way into a new exhibit on whales
here at the American Museum of Natural History.

“It’s odd to
have a big predator in this hoofed plant-eating mammal group,” said John
Flynn, co-curator of the exhibit, referring to the group to which
whales and the now-extinct Andrewsarchus belonged. “But if you
think about it, some of the other relatives like pigs and peccaries are
pretty ferocious and will eat just about anything.”

In an artist’s rendering, the 45-million-year-old Andrewsarchus
has a profile not unlike a giant feral pig with a more streamlined
snout. This 6-foot-tall creature lived solely on land, but its relatives
began taking to the water and eventually left land completely. [Whale Gallery: Giants of the Deep]

The “first whale,” a creature whose lifestyle (living on land but
eating fish from the nearby sea) represented the early stage of this
transition into the water, was a wolf-size fish eater that lived about
50 million years ago on the edges of the ancient Tethys Sea, according to the exhibit.
Written By: Wynne Parry
continue to source article at cbsnews.com

5 COMMENTS

  1. I’ve often wondered if today’s seals, sea lions, and sea otters are in the process of becoming completely aquatic. Most of them come ashore only to give birth and are awkward on land but fantastically graceful, athletic and swift in the water. Maybe there descendants will eventually become whale or dolphin-like…

    • In reply to #1 by Sue Blue:

      I’ve often wondered if today’s seals, sea lions, and sea otters are in the process of becoming completely aquatic. Most of them come ashore only to give birth and are awkward on land but fantastically graceful, athletic and swift in the water. Maybe there descendants will eventually become whale or dolphin-like….Evolution doesn’t work quite like that , something could put pressure on them to go back to land or at the extremes even fly , evolution has no direction , its kind of retrospect :)

  2. Heigh blue, iv often thought that myself, it looks like seals/sea lions are in the process of evolving into mammals more a kin to dolphins, some whales have a relic of a leg bone that remains in their body today but has no practical use its proof that the ancestors of whales ones walked on land and that natural selection has almost fazed out the legs altogether.

  3. National Geographic did an 8 page article on whale evolution in 2010. (see links)

    It has this nice interactive animated graphic showing the transitional evolution from land to sea.

    http://ngm.nationalgeographic.com/2010/08/egyptian-whale/whale-animation

    Valley of the Whales (8 pages)

    An Egyptian desert, once an ocean, holds the secret to one of evolution’s most remarkable transformations.
    http://ngm.nationalgeographic.com/2010/08/whale-evolution/mueller-text

    http://ngm.nationalgeographic.com/2010/08/whale-evolution/barnes-photography – PHOTOGRAPHS – showing the archaeologists at work in the desert, and the bones they found. – Including a fossil whale leg! (It’s the last photo in the series)

    The 18-inch-long hind legs of Basilosaurus (left leg, above) were far too small to support the whale’s massive 50-foot-long body. In fact, the creature never left the water. But the retention of legs is dramatic evidence that earlier whales once walked—and ran—on land. No one knows for sure how Basilosaurus used its tiny legs; paleontologist Philip Gingerich believes they may have served as stimulators or guides during copulation.

  4. Here’s the penultimate paragraph from the article in National Geographic:

    Gingerich is still baffled by the conflict that many people feel between religion and science. On my last night in Wadi Hitan, we walked a little distance from camp under a dome of brilliant stars. “I guess I’ve never been particularly devout,” he said. “But I consider my work to be very spiritual. Just imagining those whales swimming around here, how they lived and died, how the world has changed—all this puts you in touch with something much bigger than yourself, your community, or your everyday existence.” He spread his arms, taking in the dark horizon and the desert with its sandstone wind sculptures and its countless silent whales. “There’s room here for all the religion you could possibly want.” 

    sigh<

    Steve

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