A tiny extant bat enters the LRT. Plus living bat ancestors bounce around on YouTube.

Before there were bats on this planet
there were mouse lemurs (genus: Microcebus, Figs 1, 2), according to results recovered by the large reptile tree (LRT, 2201 taxa). Traditionally mouse lemurs have been considered to be the smallest > primates Notharctus, and extant lemurs. This is the basal dichotomy that splits bats from primates. There is nothing superficially bat-like about mouse lemurs. The skeletal elements tested in the LRT recover Microcebus as a bat ancestor.

Isn’t it ironic that the decades long search for a bat ancestor
was under the nose of academics all along, but excluded from prior bat studies. We’ve seen omissions like this many, many times before in paleontology.

Bats (worldwide) and mouse lemurs (Madagascar)
probably went their separate ways 150 to 200mya, during the Jurassic with Madagascar drifting away acting as a refuge for primitive vertebrates from birds to tenrecs to basal placentals. Similarly, basal primates and mouse lemurs went their separate ways a little earlier.

Dr Anne Yoder of Duke University describes
their dementia studies with mouse lemurs. She describes them as the smallest primate, but that’s only when bats are excluded from analysis. The LRT minimizes taxon exclusion by testing so many traditionally omitted taxa.

The smallest living bat,
Craseonycteris (Hill 1974,Thailand), was just added to the LRT (2201 taxa). No surprise, it nests with Mystacina, the New Zealand lesser short-tailed bat.

Despite its diminutive size,
Craseonycteris is not the most primitive known bat (Fig 4). Craseonycteris became a smaller version of more widespread Mystacina, probably due to its isolation on the coast of Thailand.

References
Gray JE 1843. List of the Specimens of Mammalia in the Collection of the British Museum, George Woodfall and Son, London.
Hill JE 1974. A new family, genus and species of bat (Mammalia; Chiroptera) from Thailand. Bull. British Mus. Nat. Hist., Zoo1. Ser., 27:301-336.
Simmons JA, Kick SA and Lawrence BD 1984. Echolocation and hearing in the mouse-tailed bat, Rhinopoma hardwickei: acoustic evolution of echolocation in bats. Journal of Comparative Physiology A 154: 347–356.

wiki/Mystacina
wiki/Craseonycteris