Researchers studying 16-million-year-old sediment in New Zealand have discovered a new extinct bat species that walked on all four limbs. And it would have been at least three times larger than today’s average bat. The findings were published in PLoS One this week.
In New Zealand’s old growth rainforests today, there are two species of native Mystacina bats, including Mystacina tuberculata (pictured above). These semi-terrestrial critters are known as burrowing bats because they forage under leaf litter and snow—scrambling along the ground on their wrists and feet (which face backwards) with their wings furled up tightly. The oldest known Mystacina bat fossils date back 17,500 years, but researchers suspect these bats have a much more ancient history in New Zealand. However, no one knows exactly when the first of these “walking” bats crossed the ditch from present-day Australia.
These new fossils—the first pre-Pleistocene record of the genus—were found in Central Otago on South Island. The sediment was left over from Lake Manuherikia, which was part of a warmer subtropical rainforest between 16 and 19 million years ago. "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," Suzanne Hand from University of New South Wales says in a statement. "This helps us understand the capacity of bats to establish populations on islands and the climatic conditions required for this to happen.”
Mystacina miocenalis fossil teeth / Rod Morris
The new species, Mystacina miocenalis, is named for its Miocene age. It had limb bones specialized for walking, like those of Mystacina tuberculata, and it even roosted in the same kinds of trees. Additionally, the new species had very similar teeth to its living relatives, suggesting how it also enjoyed a broad diet of nectar, pollen, fruit, insects, and spiders—prehistoric cousins to those eaten by Mystacina bats today.
What’s noticeably different is the size difference: At an estimated 40 grams, the spectacularly large extinct bat would have weighed three times that of its living Mystacina bats, as well as that of the average of 900 bat species alive today. "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 adds. "The unusually large size of this bat suggests it was doing less in-flight hunting and was taking heavier prey from the ground, and larger fruit than even its living cousin."