Teeth and bones of the extinct bat - which was about three times the size of an average bat today - were recovered from 16 to 19-million-year-old sediments near the town of St Bathans in Central Otago on the South Island.
Burrowing bats are only found now in New Zealand, but they once also lived in Australia, according to researchers at the University of New South Wales (UNSW).
Burrowing bats are peculiar because they not only fly; they also scurry about on all fours, over the forest floor, under leaf litter and along tree branches, while foraging for both animal and plant food.
With an estimated weight of about 40 grammes, the newly found fossil bat named Vulcanops jennyworthyae was the biggest burrowing bat yet known, researchers said.
It also represents the first new bat genus to be added to New Zealand's fauna in more than 150 years, they said.
"They are related to vampire bats, ghost-faced bats, fishing and frog-eating bats, and nectar-feeding bats, and belong to a bat superfamily that once spanned the southern landmasses of Australia, New Zealand, South America and possibly Antarctica," said Hand, first author of the study published in the journal Scientific Reports.
New Zealand's burrowing bats are also renowned for their extremely broad diet.
"They eat insects and other invertebrates such as weta and spiders, which they catch on the wing or chase by foot. And they also regularly consume fruit, flowers and nectar," said Hand.
"However, Vulcanops's specialised teeth and large size suggest it had a different diet, capable of eating even more plant food as well as small vertebrates - a diet more like some of its South American cousins. We do not see this in Australasian bats today," she said.
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