Can't tell from the bark, could be any of at least several Sec. Macrantha maples. And hybrids between them occur among cultivated specimens in collections - one of the distinctive features of Acer capillipes is that it tends to come true even when exposed to other species. So if the original tree was, in fact A. capillipes then your seedling may have characters of pure A. capillipes.

It looks to be the same as my original, but has really taken a beating over the years due to ice and wet snow.
Here's the original. You can see why I didn't want it on my drainfield and why it was out of scale with the upright Japanese Maples around it.
Mike