I found a woodland mansion in the outer edge of my achievement world after expanding it from medium to full size. I told my friend, since we both needed the achievements for exploring one of these things, and in we went.
On the second floor, I found... a fossil.
Last I checked, fossils are supposed to spawn underground in swamps and deserts. The second floor of a woodland mansion does not count as either or those two biomes, nor is it underground. Then up on the third floor, there was part of another one poking through the floor (I did not think to look up when I was on the second floor, though).
Interesting structure generation hiccup there. Methinks this update is still a little glitchy.