January 7 -- whales

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One of the paleontologists at the University of Michigan is particularly interested in the evolution of whales. 

Whales evolved from four-legged land mammals.  Their nearest relatives who still live on land are currently thought to be hippos.

Note the remnants of pelvises and/or hind legs.....

These are difficult conditions for photography -- it's dark in there, and some of these skeletons are large (so parts of them are pretty far away from the lens!).  The blurrier skeleton here is 45' long.....

And still has the remnants of a pelvis and hind legs.....

Here's the front end, relatively clearly depicted.  I wonder about those small front legs.  Modern whales have big front "legs".....  I wonder if Basilosaurus isis was on its way to becoming something even more snake-like than this skeleton indicates.....  It's hard to imagine those tiny front legs were very useful. 

But then -- I think it's hard to imagine T. rex's tiny front legs were useful, and yet the marks on its bones where the muscles were attached show those little front legs were controlled by big strong muscles, which means those legs must have been used, and used strenuously...........

I didn't see info speculating about the use of these little front legs.

This info isn't that easy to read (though you can, as always, click on the image to embiggen).  It says that no other snake-like whale, past or present, is currently known.

This model was directly above the info above -- the "please touch" refers to this....  I'm surprised by the relatively tiny size of the eye.  I wonder how it found its prey.  I don't know when echolocation evolved......

Like the allosaurus head model we looked at yesterday, this one shows what the live creature may have looked like, on one side, and shows the skull on the other.  Look at the teeth!  This is no reptile -- the teeth in the front of the mouth look very different (and, presumably, have a different function) from the ones in the back.  We already knew this was a mammal, so we are not surprised to see it has differentiated teeth.

Look at the size of these jaw muscles!  The info on this side of the model says this critter had a very powerful bite........

As the nearest land-living relative of whales is currently thought to be hippos, it's not a surprise that there is a hippo skull in this part of the museum.

Do you remember, when we last went to the Toledo zoo, we saw the hippos enjoying pieces of fruit?  I got lots of close-ups of hippo faces.  I was surprised, back in August, to see that the hippos' noses had a big ridge of bone down the middle.  Their faces were not flat on top, as I would have said they were, before photographing them that day.

This skull clearly shows that ridge.

It makes me happy to compare things I saw or learned one day to something I see or learn on another day.....

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