…even so, the resemblance
clearly shows what pre-bats were like (Fig. 1), and not by convergence. Caluromys (right) is the last of the marsupials, transitional to basal placentals. Bats, like Pteropus (left), are not too far from basal placentals.
Caluromys is in the ancestry of bats
in the large reptile tree (LRT, 1272 taxa). Caluromys shows where bats inherited their signature inverted posture, even though that genus is several nodes away from Pteropus.
Since Caluromys is basal to all other placentals,
maybe bats aren’t the odd ones after all, for hanging inverted. It’s the primitive way to go. All the other placentals that stopped hanging inverted are the derived ones.
We looked at the origin of bats
here and in earlier posts linked therein.