Good morning, John.  It is time for another Bizarre Beasts.  This time I've taken a different tactic and I'm approaching an animal that you are familiar with, but that is way weirder than I thought.  Just because something is common doesn't mean it's not bizarre, and John, horses.  Horses!  They can't puke.  They can't breathe through their mouths.  I mean, I'm not saying they aren't beautiful animals, though, in part, they were bred to be beautiful. 

It's important to note that there are kinda no wild horses.  Now, there's two reasons for that kinda.   First, there are lots of feral horses.  These are wild individuals of a domesticated species and there are tens of thousands of feral horses in North America.  But the second reason it's a kinda is more interesting.  In Mongolia, there's a species of horse that went extinct in the wild but has now been reintroduced.  It's called Przewalski's Horse, or the Taki and it's often called the last wild horse, but first, this probably isn't the horse that modern horses were domesticated from, at least not entirely, and second, genetic studies indicate that the Taki might actually be a feral descendent of an ancient domesticated horse, but here's the thing.  For thousands of years, wild horse herds and domesticated horse herds existed in the same spaces.  So there isn't really a clear sharp line between domesticated horses and wild horses, but the Taki with its short legs and zebra-like mane is likely a good approximation of what horses looked like before we got our hands on them, and whether or not modern domesticated horses are descended from Przewalski's Horse, maybe some but probably not entirely.  

A big piece of that would also be tarpons, a wild horse that is now entirely extinct, and maybe we have a photo but we definitely have a drawing of.  One single drawing.  That's what we have.  Or we could look to cave paintings, because these are actually the only images we have of pre-domestication horses.  Now, we often think of horses as being a Eurasian thing, but they actually evolved in North America before barely getting out over the Bering land bridge before going extinct, and then we humans brought them back because they were useful and then they escaped and became wild and so that famous North American mustang is kind of an invasive species, but it's also kind of a reintroduced species.

As far as I know, that is the only example of that ever happening in history.  All that is very cool, but the thing that really freaks me out about horses is their legs.  Okay, a thing you have to understand, all terrestrial vertebrates have a really similar body plan.  We have two forelimbs and we have two hind limbs and we have a middle trunk and we have a head on top, and at the end of each limb, we have feet.  Okay, in a few species, there are hands, which are just like feet that you don't walk on in bats, you have feet that you fly with.  Birds, their feet just became this like, little nubbin on the end of their arms.  This sounds strange, but to an evolutionary physiologist, like, hands are just feet that you type with.  

Whatever, I don't have time to talk about how weird hands are.  The point is, there's a very similar body plan in all animals.  In us, we have bone, bone foot.  In ostriches, bone, bone, foot.  In mice, bone, bone, foot.  In Tyrannosaurus Rex, bone, bone, foot.  But then, you've got a horse leg.  That's bone, bone, bone, bone, bone, foot?  Where's the--where's the foot?  The species in Equis, which includes horses and zebras and donkeys are just not closely related to any living species, but in the fossil record, we can see their toes becoming less and less necessary until they are left walking around on just one big toe.  Those two top bones are leg bones.  All of the rest of these bones are foot.  They're foot bones.  And the horse hoof is just a big old toenail.  

So the next time you see some beautiful galloping stallions, just note, they're all just walking around on one finger.  If you look close enough, John, everything is a bizarre beast, though next time we will return to some beasts you are less familiar with.  John, I'll see you on Tuesday.