Scientists have discovered the fossilized remains of a new "walking" bat species, which lived 16 million years ago, and roamed ancient New Zealand.

According to a study published in the journal PLOS ONE, Mystacina miocenalis walked on four limbs and was three times larger than today's average bat. Interestingly, it's even related to another bat, Mystacina tuberculata, which still inhabits New Zealand's old growth forests.

"Our discovery shows for the first time that Mystacina bats have been present in New Zealand for upwards of 16 million years, residing in habitats with very similar plant life and food sources," lead author and vertebrate palaeontologist Suzanne Hand, from the University of New South Wales (UNSW) in Australia, said in a press release.

The fossils were found near Central Otago on South Island, in sediment left over from a vast prehistoric body of water known as Lake Manuherikia, which was part of warmer subtropical rainforest during the early Miocene era, between 16 and 19-million-years-ago.

These bats were believed to have an ancient history in New Zealand, but until now, the oldest fossil of a Mystacina bat found in the region dated back 17,500 years ago. This latest discovery makes scientists question when these strangle walking bats first arrived to New Zealand.

"This helps us understand the capacity of bats to establish populations on islands and the climatic conditions required for this to happen," noted Hand.

"Bats are important pollinators and seed dispersers that keep forests healthy. Understanding the connectivity between the bat faunas of different landmasses is important for evaluating biosecurity threats and conservation priorities for fragile island ecosystems," she added.

The new species is similar to its contemporary relative in that it has similar teeth - most likely used for a balanced diet of nectar, pollen, fruit and insects. Limb bones found in the deposit also showed similar structures specialized for walking.

Where they differ, however, is in body size. M. miocenalis weighs about 40 grams, which is three times heavier than M. tuberculata and 900 other living bat species. Due to its abnormally large size, researchers believe the new species was more adept at hunting on the ground than in the air.

"The size of bats is physically constrained by the demands of flight and echolocation, as you need to be small, quick and accurate to chase insects in the dark," Hand explained.

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