I believe that sometime after the arrival of Spanish horses there were wasp some brought by Norse sailors, but bing is only giving me very narrow search results.
I know there’s an island somewhere off of the Carolinas with a protected herd of horses, and I don’t think the Spanish supplied that line.
Even though the horses which were here went extinct, the arrival of another horse supply came pretty long ago.
As @Demosthenes says, we had some very cool mammals here which met with extinction not so very long ago, by anthropological terms.
There was giant sloth, sabor tooth cats, horses, camels, bison, plus beaver big enough to make a full length coat from one animal.
We missed out on a lot of very cool stuff by only a few centuries!
Wait, I forgot to mention woolly mammoth. How could I forget them?!
How cool would it be to have a mammoth ranch?