A few weeks ago, researchers in New Zealand announced the discovery of a previously unknown fossil bat from the early Miocene. Mystacina miocenalis, as it has been named, is thought to have been roughly three times larger than average modern bats (flying foxes excepted of course).
Mystacina miocenalis is thought to be ancestral to two extant species which still inhabit New Zealand, Mystacina robusta and Mystacina tuberculata. Although other fossil bats from the Mystacinidae family have been found in New Zealand, they come from deposits which date to the Pleistocene epoch (2.8 million to 11 thousand years ago). With a date of 16 million years old Mystacina miocenalis shows that the Mystacinidae family is much older than previously believed.
In the PLoS article which describes this new fossil discovery, the researchers suggest that Mystacina miocenalis likely occupied a similar ecological niche as the two extant species.